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 can't say that I grew up eating cole slaw, nor was it love at first taste. My earliest experience with it was when the lady behind the bulletproof glass at the KFC on 125th street (this was back when there was bulletproof glass and KFCs everywhere in Harlem) mixed up my order and gave me a cup of their slaw instead of the mashed potatoes and gravy. She didn't seem like the kind of cashier who enjoyed confrontation, so I picked up my spork, bucked up, and dug into that mayo-doused cup.
Needless to say, I stayed away from the stuff for years following that harrowing experience. It scarred me enough to steer clear of not only slaw, but mayo altogether, for a good decade.
I didn't truly start loving cole slaw until I tasted the excellent version that Barbara Lynch makes at her B&G Oysters in Boston's South End. Rather than soupy or gloppy with excess mayonnaise, the slaw there is tangy and fresh, with just a hint of creaminess to bind it together.
Since that day, I've come to enjoy cole slaw in all its various regional forms, from the bright yellow mustardy stuff I first tasted at my cousin's Tennessee wedding to the vinegary chopped slaws I had in Eastern North Carolina. Slaw and I may have met rather late in life, but we're more than just friends these days—we're in a full blown relationship, and it's high time that I properly acknowledge it on this site.
For the sake of simplicity, today we're going to be dealing solely with my first true love, cream slaw, but we may well come back to address other varieties in the future.
As with many good stories, this one starts with cabbage.
Cabbage comes in three main varieties:
- Green cabbage is the cheapest and most common. It has large smooth leaves, a fairly compact head, and distinct aromas of sulfur that can turn rather pungent when cooked. This is a fine choice for slaw.
- Red cabbage has the same smoothness and general shape as green leaf cabbage with a slightly crunchier texture and a more assertive peppery flavor. Some people like red cabbage slaw; I personally find it too crunchy, and reserve it mostly for pickling. When working with red cabbage, make sure to use stainless cookware in order to prevent the cabbage from discoloring to a disturbing dirty blue color.
- Savoy cabbage is the most delicate in flavor of the three. It has thinner, wrinkled leaves, and a very tight and compact head. For this reason, even a small head of savoy cabbage will expand to a large volume once the leaves are slivered and separated.
This is not my first time around the block with cabbage, but as with slaw itself, cabbage and I have invested in a fairly long-term relationship with each other, which means that every once in a while we have to sit down like full-grown brassicas, have some serious head-to-head* discussions, and come up with a new set of boundaries and goals by which to define our relationship.
*head-to-head, get it? >_
All this is to say that while at one point I thought I enjoyed the delicate, non-sulfurous flavor of savoy cabbage in my slaw, after some more serious side-by-side testing, I found that the crunch and assertiveness of green cabbage was actually the way to go.
Speaking of crunch management, this brings us to the first order of business: purging the cabbage.
See, unlike a normal salad in which tender greens are tossed with a dressing mere moments before serving, so that the leaves stay bright, fresh, and crunchy, cole slaw requires a pre-treatment. Don't believe me? Try it out for yourself: just dress up some shredded cabbage and see what happens. But I'm warning you, it's not pretty.
First, it ends up far too crunchy, with tough, raw-tasting shreds of cabbage. Second, it ends up expelling way too much liquid. Add enough dressing to flavor it properly, and you end up with cole slaw soup:
See? I told you, not pretty.
What we need is a way to tenderize it while allowing it to maintain some of its crunch, simultaneously achieving a depth of flavor without drowning it in dressing. How do we accomplish this?
There are two steps in the process. First is in the cutting. While in some regions of the country, chopped slaws are common, what we're going for today is a fine shred. For great slaw, you want to go pretty darn thin—I like to pull out my Benriner mandoline for the task (though to be honest, I'm the kind of guy who likes to pull out the mandoline whenever the urge strikes. In this case, it happens to be an appropriate urge. This is not always the case).
What's the goal of this shredding? Well, first, it shortens tough fibrous sections of the cabbage along one axis, making it more tender to the bite. More importantly, it allows us to accomplish the second step in Project Tenderize: it exposes more cells to the moisture-sucking effects of salt.
You can imagine your cabbage slices as a series of teeny, tiny water balloons. When the cabbage is fresh, the balloons are all filled with water, causing them to stretch out and stay stiff. Your goal is to release a bit of this water, so that the cabbage will soften up a bit. Salt achieves this goal through the process of osmosis—the tendency of water to travel across a permeable membrane from the region of lowest solute concentrate to highest. That's a lot of big words, but culinarily speaking, all it really means is that water has a tendency to move from a less salty place (in this case inside the cabbage) to a more salty place (outside the cabbage).*
*This, by the way, is true of all sorts of foods, not just cabbage! Think: salt-cured meats like bacon or prosciutto, or preserved items like naturally fermented pickles, sauerkraut, and preserved lemons. Fresh meats behave a bit differently—see here for the truth about brining.
This migration of water (and the subsequent softening of cabbage) is dependent on how much salt is added: the more salt you add, the more water it will draw out. To demonstrate this, I salted four 100 gram batches of shredded cabbage with 1/4 teaspoon, 1/2 teaspoon, 1 teaspoon, and 1 tablespoon of salt, respectively, which corresponds to concentrations of 1%, 2%, 4%, and 12%. Each batch of cabbage was left to drain for 30 minutes before being lightly squeezed to remove excess moisture.
The level of moisture reduction isn't directly proportional to the amount of salt added, but cabbage with a 12% salt purge still loses more than three times as much moisture as cabbage with 1%.
And what about flavor? For frame of reference, the saltiest sausage you are likely to eat has between 2 and 3% salt by weight. With our cabbage, on the other hand, even the cabbage salted at 4% didn't taste particularly salty—most of the excess salt gets removed along with the purged liquid (12% salt did prove too salty to be palatable). As far as balance of flavor and texture goes, the 2% batch was the way to go. At least for now.
On to the next question...
So we know that some amount of purging is necessary if you want your cabbage to hit that magic crunchy-but-tender spot, and our initial testing has shown that the amount of salt that you purge with can directly affect the amount of liquid drawn and the final texture of the cabbage. But what about timing? How long is the ideal purging time? Existing recipes run the gamut from no pre-salting, to salting for up to three whole hours in advance. We tested it out by salting shredded cabbage with 4% salt by weight and letting it sit in a bowl before draining in a colander and pressing out excess free moisture.
Here's what we found:
|Salting Time||Moisture Loss (% Weight)|
Well would you look at that? Turns out that after 15 minutes of salting, you've pretty much drawn out all of the moisture you're ever going to. Heck, after even 5 minutes of salting, you've got most of it done. That's good news for those of us who like to get things done as quickly as possible (and bad news if you're the type who likes to catch an episode or two of Good Eats while you wait for your cabbage to purge. You'll just have to get your Alton dose later).
In our taste test, it turns out that most folks prefer the texture of the minimally-purged cabbage—a quick, five minute purge came out as the clear winner, with anything over 15 minutes being judged as slightly too soft.
This presented a problem: given that we were going with the 2% of salt we'd settled on earlier, a 5 minute purge time produced the best texture, but longer purge times produced cabbage with a deeper, more concentrated flavor.
Was there a way to hit both goals at once?
Well, knowing that the amount of liquid lost (and therefore the level of flavor concentration) is related to the amount of salt used in the initial purge, what if rather than using just 2% salt for my purge, I went back and re-visited the 12% version? Only this time, purging for only 5 minutes in order to rapidly concentrate the cabbage before rinsing off the excess salt in cold water to immediately halt the process once the ideal level of tenderness was reached?
The method worked. Sort of. While the cabbage flavor was concentrated enough that I could get away with a reasonable amount of dressing, the cabbage was coming out too salty, despite a thorough rinse, and it was still slightly too beat up by the time we were done with it.
Food Lab Assistant Extraordinaire Luke Davin suggested that perhaps the textural issues were not arising due to purging problems, but because of the mechanical action of squeezing excess moisture out of the cabbage.
For our next test, I also replaced some of the salt in the initial purge with sugar—another osmosis-inducing solute that could serve to balance out flavor. This time, immediately after rinsing, we spread the slaw mixture out onto a bed of paper towels and dried it gently by hand.
A-ha! Those two elements unlocked the key to the puzzle. We now had cabbage that was perfect for slaw: concentrated in flavor with a good balance of salt and sugar built right in, tender but still vibrant and crunchy. Not only that, but we got our cabbage ready-to-dress in record time!
See the squeezed-dry cabbage on the left and the toweled-try cabbage on the right?
The rest of the process was a relative cakewalk.*
*NB: subsequent testing showed that for large batches, the paper towel-averse can also use a salad spinner to gently spin their cabbage to dryness after the initial purge-and-rinse stage.
The Other Players
Dressed cabbage is the only truly essential player for real cole slaw, but a few judiciously chosen additions never hurt nobody. For my slaw, I go with a simple mix of thinly sliced red onions, a touch of chopped parsley, and some grated carrots.
The only thing to bear in mind is making sure to hold the carrot at the proper angle when grating:
The photo on the right is the is the wrong way to do it, while the photo on the left is the right way, and here's why:
See the nice long strands you get by holding your carrot at a bias? That's what we're going for here. Long carrot strands.
As far as dressing goes, mayo is a given, as is a good amount of cider vinegar. I fiddled with a number of ratios until I landed on 3 to 1, mayo to vinegar. A touch of dijon mustard brings a bit more heat and vinegar to the table. The goal is just enough to step on your toes a bit, not a big punch to the gut.
Other than that, it's plain white sugar to balance out the salt and vinegar (I also tested agave nectar, brown sugar, and honey—none save the honey made any kind of detectable difference), and a ton of black pepper.
Ok, not a ton. But a lot. I may or may not have over-peppered several batches of cole slaw at the office during testing phases, but in any case, believe me: you want to use more than you think is a reasonable amount. Cabbage and pepper are very good friends.
Because our cabbage is already so flavorful with its salt and sugar cure, and its got a relatively low moisture content from our careful drying, you can get away with using a very minimal amount of dressing, giving it intense, concentrated flavor without turning it into a soupy mess.
Oh cole slaw, I never knew ya'!
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.