How to Marinate and Grill Flank Steaks
It's hard to think of a cut of meat that is more conducive to cooking for a crowd than flank steak. It's got a robust, beefy flavor and a pleasantly tender texture with a bit of good chew. It comes in large, regular shapes that make cooking, slicing, and serving easy, and they're just thin enough that they'll cook through in a matter of minutes, but just thick enough that you can still get a nice, medium-rare center.
They're pretty diverse as far as cooking method goes, but the best way, by far, during the summer is on the grill. With their large surface area, they're made for picking up nice char, smoky flavors, and the types of dishes they transform into seem perfect for al fresco dining.
Here are a few tips for marinating, grilling, and serving flank steak.
At one time flank steak was a relatively hard cut to find, reserved for specialty butchers or saved for industrial uses. These days, consumers are wise to its benefits, and it has become as near-ubiquitous a cut as the standard high end steaks.
When shopping for flank steak, look for an even, deep red color with a fair amount of fine fat running along the length of the muscles. Poorly butchered flank steak will either have a thin membrane still attached to parts of it, or will have had that membrane removed so aggressively that its surface has been shredded. Look for smoothly textured pieces without nicks or gouges.
A standard whole flank steak can weigh anywhere between two and four pounds. Plan on cooking a pound of flank steak for every three diners, a pound and a half if your friends are as hungry as mine.
Contrary to what you may think, marinade actually does not penetrate particularly far into meat—even over the course of a few days, the bulk of the aromatic compounds in a marinade will travel mere millimeters into the meat (the exception being salt, small sugar molecules, and some acids). In reality, a marinade is mostly a surface treatment, and not much benefit lies in marinating for more than half a day or so. If you'd like the flavor of the marinade to completely coat your meat, your best bet is to reserve some marinade and simply toss your meat with it after it has been cooked and sliced.
Here are a few ingredients you should consider when constructing a marinade:
- Salt is absolutely essential. It is one of the few ingredients that penetrates and seasons meat deeper than the outer surface. I like to add my salt in the form of soy sauce or fish sauce, which are also very high in glutamates, adding extra savoriness to my meat.
- Sugar when used in moderation will help the meat brown better on the grill, creating strong smoky, charred flavors. A touch of sugar also balances salt nicely.
- Aromatics are mainly a surface treatment, but they can still be quite powerful. Garlic, shallots, dried spices, herbs, or chilis are all good things to experiment with.
- Oil is often a primary ingredient in marinades. Many aromatic compounds, such as those found in garlic, are soluble in oil but not in water. The oil will help spread these flavors evenly across the surface of the meat, as well as lubricating and protecting the meat when it first hits the grill.
- Acid can balance flavors, but should be used sparingly. It can denature proteins in the meat, causing it to turn mushy over time. With very acidic marinades, it's particularly important to not overmarinade—certainly no more than half a day.
As far as specific flavorings go, just go wild. My absolute favorite way to marinate flank steak is with a sweet and spicy Thai-style sauce. I make mine with palm sugar (brown sugar will do fine), dried Thai chili flakes, fish sauce, garlic, and lime juice, which I then split in half, reserving half to toss with the meat after cooking, and adding some oil to the other half to use as a marinade.
Once the meat is cooked, rested and sliced, I toss it all together with some reserved marinade, and a big herb salad with shallots and bean sprouts. It gets an awesome caramelized, charred crust on the grill from all the sugar, and the great thing is that it's delicious even when cold, making it the perfect dish for potlucks or relaxed backyard parties.
While fajitas are more commonly made with skirt steak, flank steak makes a fantastic filling as well. It may seem out of place in a Mexican (or Meximerican) recipe, but soy sauce is actually quite a common fajita marinade ingredient. I mix mine with oregano, ground ancho chile (or if I'm lazy, chili powder), cumin, garlic, and sugar, oil, and lime juice. You can go all out and serve it restaurant-style with grilled peppers and onions, but that's just gilding the lily—well-cooked meat doesn't need much more than a squeeze of lime, some chopped onions and cilantro, and s bit of fresh salsa.
If you're in more of a steakhouse mood, a Worcestershire and anchovy-based marinade delivers classic A-1 flavor (albeit in a much, much tastier form than the bottled glop).
Cutting some Worcestershire sauce and chopped anchovies with a bit of soy, a good amount of Dijon mustard, some sugar, and garlic, then shaking the whole thing up with oil creates a creamy, emulsified marinade that works equally well as a sauce.
How to Grill
The key to perfectly grilled flank steak is to use a modified two-level fire—that's a fire where all the coals have been pushed over to one side, leaving the other empty (in a gas grill, just leave one bank of burners off). Doing this gives you more control over your cooking, allowing you to sear your meat over the crazy hot side, and finish cooking it through gently with the cover on on the cooler side of the grill. Without this option, there's a good chance that you'll end up incinerating the exterior of your meat before the center cooks through.
Before applying a marinated steak to the grill, it's important to wipe it off using a paper towel. Wet meat can cause a couple problems. First, if the wetness is oil-based, it'll drip down into the fire causing flare-ups that will deposit foul-tasting sooty compounds on your steak. If there's too much water based moisture, your meat will end up steaming instead of searing, and nobody wants to eat marinated steamed flank steak, do they?
Carving and Serving
Like with all grilled, seared, or roasted meats, it's vital to allow the steaks to rest before slicing into them. As we demonstrated here, cutting into your meat prematurely leads to loss of juices and flavor. A good rule of thumb is to let the internal temperature of your meat drop to a couple of degrees below the maximum cooking temperature. So if you cooked your flank steak to 130°F for medium-rare, you should let it rest until it drops to 128°F before slicing. For a flank steak, this takes 5 to 10 minutes.
As for slicing it, we're lucky on this front—a flank steak has a distinct grain, making it very easy for us to properly orient a knife for carving. You always want to cut perpendicular to the grain in order to minimize the length of each muscle fiber you have to chew (for more information on this, see our article here.
This should be done as soon as possible, using the appropriate utensils and degree of reckless abandon.