Liquid smoke
Worcestershire sauce
Soy sauce
Flank steak
Peppers & onions, sliced
Flour tortillas, warmed

Make marinade of equal parts liquid smoke, Worcestershire sauce, and soy sauce. Marinate steak in this before grilling for 2 to 3 hours (or more). While grilling steak, pour marinade over peppers and onion and saute in skillet until soft. Slice steak in thin slices against the grain. Mix with peppers and onions. Fill flour tortillas and roll.