Steak is usually best when it's simply prepared. For steak tacos, I wanted to make a flavorful marinade without overpowering the natural flavors of the beef. I came across this recipe from Rick Bayless's site, FronteraKitchens.com. The original recipe included directions for a roasted poblano rajas (rajas refers to strips of chiles in Mexican cooking terms.) I opted not to make the poblano rajas as the recipe was written but I did substitute the poblanos with bell peppers instead. To add some variety, I also used the same marinade for chicken which came out wonderfully too!
recipe from Rick Bayless
1/2 medium white onion, sliced
3 garlic cloves, peeled and roughly chopped
3 tablespoons fresh lime juice
1/4 teaspoon cumin, preferably freshly ground
1 pound skirt steak, trimmed of surface fat as well as the thin white membrane called “silver skin"
A small bowlful of lime wedges for serving
12 fresh, warm corn tortillas
Taco condiments of your choice
Grilling the meat. Remove the steak from the marinade and gently shake off the excess. Oil the steak well on both sides, and lay it over the hottest part of the grill. Grill, turning once, until richly browned and done to your liking, about 1 1/2 to 2 minutes per side for medium-rare.
Serving the tacos. Cut the long piece of skirt steak into 3- to 4-inch sections, then cut each section into thin strips across the grain (that is, in line with the full length of the skirt steak). Set on the table, along with the lime wedges and hot tortillas with your preferred condiments for your guests to make into soft tacos.
Working Ahead: Thin steaks like skirt, taste best with a shorter tour in the marinade–1 to 8 hours. Leave them longer and the marinade flavor overpowers and saps the rosy color of the meat. The poblano-and-onion rajas can be made several hours ahead and left at room temperature; rewarm before serving. The steak, of course, must be grilled when you’re ready to eat.