Trim fat from steak, and score a diamond pattern on both sides of steak.
Combine juice and next 7 ingredients (juice through garlic) in a small bowl. Divide marinade equally between 2 large zip-top plastic bags, adding steak to 1 bag and chicken to the other. Seal bags, and marinate in refrigerator 6 hours or overnight, turning bags occasionally. Remove steak and chicken from bags, discarding marinade.
Prepare grill or broiler.
Place steak on a grill rack or broiler pan coated with cooking spray, and cook 10 minutes on each side or until desired degree of doneness. Cut steak diagonally across grain into thin slices. Place chicken on grill rack or broiler pan coated with cooking spray; cook 6 minutes on each side or until done. Cut chicken into thin slices.
Heat oil in a large nonstick skillet over medium heat. Add onion and bell peppers; sauté 10 minutes or until onion mixture begins to brown.
Warm tortillas according to package directions.
Spoon steak or chicken, onion mixture, tomato, and cilantro down center of each tortilla; roll up.