It's time for another round of The Food Lab. Got a suggestion for an upcoming topic? Email Kenji here, and he'll do his best to answer your queries in a future post. Become a fan of The Food Lab on Facebook or follow it on Twitter for play-by-plays on future kitchen tests and recipe experiments.
I have been working on this recipe for longer than any other recipe I've ever worked on. The number of times I've told Erin, "Sure, go ahead and put it on the schedule for next week," only to swap it out at the last minute because I wasn't happy with the results is a number higher than I care to count. But at long last, I'm pretty darn pleased with the results.
It all started about a year and a half ago when the good folks at Columbus Food Adventures took me on a whirlwind taco tour of Columbus, Ohio, which, believe it or not, has some of the finest taco trucks in the country. Particularly impressive were the tacos al pastor from Taqueria Los Guachos.
There, in true al pastor form, the taqueras marinate thin, thin slices of pork shoulder in a mixture of chilies and aromatics colored bright red with achiote. The slices are then stacked onto a vertical skewer, forming a large, bell-shaped trompo (spinning top), which gets topped with an onion and pineapple, and slowly rotates in front of a vertical grill. If there's a reason it resembles shawarma or doner kebab, it's because the concept was first introduced to Mexico by Lebanese immigrants.
As the trompo spins, it slowly cooks, the fat from the pork shoulder dripping out and across the surface of the meat, basting it as it crisps. As each outer layer of meat crisps up, the taquera shaves it off with a sharp knife, catching it in a soft corn tortilla before topping it with a bit of the roasted pineapple, salsa, and cilantro and onions. It's really glorious stuff. Juicy and crisp with a deep chili flavor tempered by sweet roasted pineapple.
It doesn't really get much smokiness, per se—the fire is usually a simple gas fire—but it does get a little bit of singed char. Those in the know will ask for theirs to be cooked up extra-crisp on the plancha after it's been sliced. The results are almost bacon-like in their succulence.
The question is: Can we replicate this at home?
The problems with such an endeavor are immediately obvious. First off, there are the basics. What's the best meat to use? How do I slice it so thin? How about the marinade? Is there an ideal time to marinate for? Then there's the issue of actually cooking the stuff. Can we replicate a vertical rotisserie? Is there some other viable option that would work?
I started off by addressing the meat. Normally, al pastor is made with boneless pork shoulder sliced super, super thin. If you are lucky enough to live near a Mexican meat market, you can probably find it right at the meat counter. The rest of us need to do a bit more work. I decided to test pork shoulder along with a couple of easy-to-find alternatives.
This is a pork shoulder:
It's a large, unwieldy hunk of meat with a couple of strangely shaped bones in the middle and a whole lot of rind. Unless you have years of experience butchering, cleaning it up without mangling it is not an easy task. So what advantages does it offer?
For one thing, it's packed with flavor. With meat, the more an animal uses a particular set of muscles, the more flavor they'll acquire. Pork shoulders are used extensively throughout the pig's life, rendering them extremely porky and full of fat and connective tissue that breaks down into rich, unctuous gelatin as it slow-roasts. But for the pork to be tender, it must be sliced thin and must be slow cooked.
This kind of slicing is not easy to do with the equipment you've got at home, which brings us to...
Pork sirloin. Cut from the pig's back towards the hind legs (the hams), sirloin is far easier to work with (it's easy to find a boneless sirloin roast), is relatively easy to slice, and is more tender than shoulder. These are all good things. The problem is that it lacks fat and connective tissue, making it prone to drying as it cooks.
The final option I tried was pork belly:
The fattiest cut of all (it's what bacon is made out of), pork belly is packed with flavor and connective tissue. It can be a little difficult to butcher properly—you have to remove the rind and any small rib bones remaining—but it's relatively easy to slice thin, and—I thought—should produce extremely juicy tacos.
I tried slicing each cut of meat (against the grain, of course!) into thin sheets, but couldn't get them as thin as needed for proper al pastor.
Instead, I resorted to pounding them flat by laying them in an opened up heavy duty plastic bag and smashing them repeatedly with the bottom of a skillet.
The resultant pieces of meat were as wide as I wanted, with the added advantage of having a small amount of tenderization occur as well.
To cook the meat, I started with a basic working marinade recipe and grilled the slices directly rather than trying to stack them and slice them—all I was interested in at this point was the flavor and texture of each cut.
Turns out that belly is fatty alright. A bit too fatty for this. Shoulder was great, but sirloin was so much easier to butcher. For the sake of ease, I decided to go with a combination of sirloin and belly.They complement each other perfectly when it comes to flavor and fattiness. Belly can be a bit tough to slice properly, but for now it'd have to do.
The flavor base for al pastor is pretty well defined. The marinade is essentially an adobo—a sauce made with chilies, garlic, and vinegar, along with whatever other aromatics you'd like.
Using fresh dried chilies is essential. They should be pliable and flexible. If your chilies are crackly, crumbly, or dry, it's because they're old and most likely, all their flavor has dissipated along with their moisture. Do yourself a solid, throw out those old chilies, and get some new ones. I found that a combination of rich and raisin-y ancho chilies along with bright guajillo chilies was a great complement to the pork. I toast them in a dry saucepan before soaking them in chicken broth
Achiote is a mildly earthy, ever-so-slightly bitter spice with a distinctive bright red color. It comes in paste, pellet, and powdered forms. I personally find the powder easiest to store and work with, though any form will do.
To get the most flavor out of it, toasting in oil is essential. For my marinade, I toast the achiote powder along with some powdered cumin and Mexican oregano.
If you are a regular reader of this column, you'd know that marinades are largely a surface treatment. That is, they don't penetrate particularly far into a piece of meat; it's on the order of a millimeter or two per day, and it gets considerably slower the deeper into the meat it gets. Point is, in most applications, there's not much reason to marinate beyond a few hours.
But there are exceptions to this rule, and they mostly involve salt.
Salt is special. See, rather than simply flavoring meat by working itself in between muscle fibers, it actually alters the structure of meat, primarily by causing certain parts of the protein myosin to become dissolvable in water.
What does this accomplish? Well, by dissolving myosin, muscle structure is greatly loosened, allowing it to retain more moisture (this is the principle behind brining), and more importantly in this case, it allows proteins between muscle groups to cross-link, causing them to stick to each other.
This is why, for instance, sausages get a nice bouncy, snappy texture, and why if you remove the salt from one, it becomes crumbly and dry (see here for more info on salting and making sausages, and here for some deeper scientific info on the process of salting meat.
This is all well and good, but why is it important to tacos al pastor?
The thing is, in a well made trompo of meat, as the carver slices meat off of it, it should come away in coherent slices, not crumbles, and it should have an almost cured, bacon-like texture—moist, juicy, and crisp as opposed to crumbly or chalky—two sure signs that there is some salting action going on. To get to this stage, you need about 1 to 2% salt per unit weight of meat, and at least a few hours of marination time.
With a good flavorful marinade, you could just grill the meat and call it a day—many respectable and delicious recipes do just that—but that's not what I'm after here. What I want is the real deal. Cured texture, crispy bits, shaved slices and all.
This requires a bit of tinkering.
Getting In Shape
My very first thought was why don't I just build a trompo in miniature?
I tried layering my marinated meat into an empty quart-sized deli container before allowing it to rest overnight (in order for proteins to cross-link and for the meat to cure slightly). I then stuck a skewer right down the middle, inverted the whole thing, topped it off with a pineapple, and built a base out of the pineapple bottom into which the skewer head could rest, allowing the whole thing to stand upright under its own support.
So far so good.
To cook it, I set up the ring from my Weber Gourmet System Wok Grate. By placing coals around the perimeter of the coal grate, as well as directly on top of the wok grate, I was able to create a vertical heating system that cooked the pork and pineapple from all sides simultaneously.
I gotta say, it looked pretty bad ass, and surprisingly, it worked relatively well, albeit with a ton of fiddling, searing my hands to maneuver sticky pork juice-covered pineapple, adding more coals after realizing it was going to take far longer than expected, entertaining guests while their pork cooked, etc.
In short, it worked, but it wasn't fun or easy.
Here's one thing to remember: cooking on a vertical spit may look like a fast cooking method—The outer layers of meat are searing and crisping after all, right?—but in reality, it's a two-stage slow-then-fast cooking process. While the taquero is busy slicing off the exterior layers of the trompo, the layers within are meanwhile slow-cooking, causing the meat to break down and tenderize. This is, in conjunction with thin slicing and curing, are why even a tough cut like shoulder can come out tender and juicy when cooked. It's only after the inner layers of meat are exposed that they fast-cook.
So why not just separate the two phases of cooking? I returned to a method I employed when making Greek-American Lamb Gyros: pack the meat into a loaf pan before cooking. By then slow-roasting it in the oven (or on the cool side of a grill), I could get the meat as tender as I liked it before slicing it and finishing it off under the broiler or in a skillet.
The method worked like a charm, especially if you let the cooked meat rest in the fridge until chilled before slicing it.
For the record, here's what insufficiently salted meat looks like when you try and slice it:
And here's how it looks if it's been salted properly.
See the difference?
The only little thorn left in my side was the pork belly, which to be frank, is not easy to come by or to slice properly. The easy solution? Just use bacon. Bacon is already cured, already thin-sliced, and once combined with the marinated meat, blends nicely into the background, adding fatty richness and juiciness without overpowering with its smoky flavor.
As the pastor-loaf cooks, it exudes a ton of juices and fat. This is OK.
The fat is the ideal medium for re-crisping the sliced meat in a skillet (and for painting onto a pineapple before roasting it), and the juices can be added to the crisped meat to add some flavor and extra moisture back to the mix.*
*Some folks speculate the the pineapple added to the top of a trompo of al pastor will tenderize the meat as it cooks. While it's true that pineapples contain an enzyme that will break down meat protein, in the case of al pastor, it does not have this effect. The enzyme deactivates due to heat long before it can get a chance to actually break down any protein, particularly in the inner layers of meat, which don't get exposed to any dripping pineapple juice until long after the pineapple has been fully cooked. The effect of the pineapple is for flavor only, thus it can be added after the fact with no real difference.
I know I've said this, but this recipe took a long time and a whole slew of failures before I finally got it right. I'd estimate in the multiple dozens of failures over the last two years or so. But when something finally works out, it makes the whole process worth it, failures and all.
I know that the dogs would agree, and not just because they got to eat most of the failures.
The one issue you may have is that, well, the recipe does take a long time. A night to cure. Another night after roasting for it to re-set and become sliceable. That said, the actual active time is remarkably low, and most of it can be done in advance. Once the pastor-loaf is cooked, it can rest in the fridge for a few days before slicing and crisping to serve, which means that if you're planning a dinner party, it only requires a few minutes of work on the day-of to get the best tacos al pastor you'll find outside of a real taqueria.
For me, that ain't a bad trade-off.
Get the Recipe!
About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.