Beer's greatest contribution to beef is its hoppy bitterness. When paired with a hearty cut of beef, a stout or porter with 5 to 7 percent alcohol by volume challenges steak's beefiness with gusto, and both elements -- the meat and the brew -- elevate each other in taste. It's the same with beer-based marinades: Add beer to a standard oil-based marinade and the beer's essence makes its way into the beef along with the complementary herbs and spices you include with it.
Consider the herbs and spices you'll use when you choose the type of beer for the marinade. If you plan on including spicy ingredients, such as chili peppers, pepper flakes or pepper sauce, use a lager. Lagers balance spiciness without detracting from it -- they temper spicy ingredients, highlighting their pungency while softening their bitterness. For an aromatic, complex marinade, use a dark beer, such as a stout or porter. Dark beers bring out the aromatic compounds in herbs and spices. Alcohol is a solvent, and dark beers, with their relatively high ABV, extract the chemicals responsible for the flavors and fragrance of herbs, spices and aromatics better than beers with low ABV. The garlic in the marinade tastes more garlicky, the basil and thyme have more fragrance, and the freshly cracked peppercorns evoke a bit of smokiness when you use a dark beer.
Herbs, spices and aromatics have little effect on the food you marinate unless you include oil. Oil acts as a carrier: It extracts the flavonoids and esters that give herbs and spices their flavor and disperses them throughout the marinade. Beer acts as a carrier, too, but it doesn't adhere to meat like oil does -- so not only does oil make marinades more flavorful, it helps those flavors stick to the meat where they can go to work. Oil does the same for the tenderizing agent in the marinade. If, for example, you use lemon juice to help tenderize the steaks, the oil helps it adhere to the meat, where it can soften the tough protein fibers. To make the marinade base, mix 1 part vegetable oil and 2 parts beer in a mixing bowl. One cup of oil and 2 cups of beer yield enough marinade for 2 or 3 pounds of steak.
A small amount of acid is needed to cut the fattiness of the oil and to tenderize the steaks. Any food acid will do -- flavored vinegar, such as apple cider, malt or white wine; lemon or lime juice; even cayenne-pepper sauce has enough acid to tenderize beef. Add 1 tablespoon of acid for every cup of oil in the marinade.
Now comes the fun part -- the flavoring. Anything goes here, but keep your choices thoughtful and composed, because adding a hodgepodge of whatever you have in the cupboard leads to a mess of flavors that lack direction. For example, for a spicy beer marinade, add one or two sliced Thai chili peppers for heat, and one or two crushed garlic cloves for pungency -- and finish with some fresh, mild herbs such as Italian parsley and tarragon to tie everything together.
Beef is naturally high in umami, a Japanese term for savoriness. Umami is also considered the fifth taste sensation -- you can't really get enough of it when it comes to beef, so adding a bit of umami to the marinade heightens the savory taste experience of the steaks. The most effective way to introduce umami to a beer marinade is with soy sauce -- it's high in glutamates, the chemicals responsible for umami, and it's also a mild tenderizer. You only need to add a few drops, just enough to taste it.
Whisk all the marinade ingredients together vigorously -- oil and water don't mix, but if you whisk briskly enough, you'll create an emulsion and the ingredients will evenly disperse throughout the oil. Next, taste the marinade and add kosher salt, pepper and sugar as needed. Place the steaks in a food-grade container or large food-storage bag. Whisk the marinade once more, and pour it over the steaks. Marinate the steaks in the refrigerator for at least two hours but not more than 12. Turn the steaks over in the marinade every few hours so all sides get equal exposure.