1. In a shallow dish, add beef. In another shallow dish, add the onion and green pepper.
2. In a large bowl, combine the chiles, lemon juice, vinegar, oil, garlic, Worcestershire sauce, oregano, salt and pepper. Pour 1-1/2 cups over meat. Pour remaining marinade over vegetables. Cover and refrigerate overnight.
3. Drain meat and vegetables, discarding marinade. Grill steak, covered, over medium-hot heat for 10 minutes on each side or until meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°).
4. Meanwhile, cut 2 pieces of heavy-duty foil into 18x12-in. rectangles. Wrap tortillas in 1 piece and vegetables in the other; seal foil tightly. Grill, covered, over indirect heat for 5-7 minutes, turning occasionally.
5. Cut steak into 1/8-in. slices across the grain; place on tortillas. Top with vegetables and roll up. Serve with avocado and sour cream if desired.
