Combine lime juice, garlic and pepper in small bowl. Place beef steaks in single layer in shallow dish. Pour marinade over steaks; turn to coat both sides. Set aside.
Heat 1 tablespoon oil in large nonstick skillet over medium-high heat until hot. Add red and yellow bell peppers and onion; stir-fry 5 minutes or until crisp-tender. Remove to medium bowl; keep warm.
Heat remaining 1 tablespoon oil in same skillet over medium heat until hot. Remove steaks from marinade; pat dry with paper toweling. Place steaks in skillet; cook 9 to 12 minutes for medium rare to medium doneness, turning 2 to 3 times. Carve into 1/4-inch thick slices.
Add beef and cilantro to vegetables in bowl; toss. Spoon beef mixture evenly onto one side of each tortilla; fold tortillas in half. Serve with salsa and guacamole, if desire
3 beef shoulder center steaks, cut 3/4 inch thick
2 tbls. fresh lime juice
2 cloves garlic, minced
1/2 tsp. pepper
2 tbls. vegetable oil
1 red bell pepper, cut into thin strips
1 yellow bell pepper, cut into thin strips
1 small onion, cut into thin wedges
1 tbls. chopped fresh cilantro
8 small flour tortillas (6 to 7-inch diameter), warmed
Prepared salsa and guacamole (optional)