Here's a fairly traditional version on the fajita: seasoned flank steak cut into thin strips.
Trim fat from steak. Slice steak diagonally across grain into thin strips. Combine steak and next 6 ingredients (steak through ground red pepper) in a zip-top heavy-duty plastic bag; seal bag, and shake well to coat.
Heat the tortillas according to package directions.
Heat 1 teaspoon oil in a large nonstick skillet over medium-high heat. Add steak, onion, and bell peppers; sauté 6 minutes or until steak is done. Remove from heat; stir in lime juice. Divide mixture evenly among warm tortillas, and roll up. Serve with sour cream. Garnish with green salsa and cilantro sprigs, if desired.