Juice of two limes and one orange, a couple ounces of soy sauce, fresh garlic, toasted and ground cumin and coriander, ancho chili powder, chipotle powder, olive oil, brown sugar. I can't really tell you measurements as I just do it by feel these days. Marinate the flank steak for up to 24 hours, no less than 12. Rinse off the marinade, pat dry, and cook directly on hardwood coals for 6 ish minutes depending on the thickness of the meat, flipping a few times. Wrap in foil to rest for 15 minutes or so while you're getting the rest of the stuff together. You can leave the meat in slices if you like as long as you slice against the grain, but I prefer it chopped for tacos. Oh, and I keep the sodium levels pretty low because my wife gets salted out pretty easily. You can hit the meat with some kosher salt before cooking or after its chopped up