Using a large knife, thinly slice steak crosswise into thin strips. Toss with chili powder, cumin and pepper.
In a nonstick skillet, heat half of the oil over medium high heat and brown beef. Remove to plate.
Add remaining oil in same skillet and sauté onion, bell peppers and cilantro for 4 minutes or until tender crisp. Return beef to skillet and heat through.
For the lime sour cream, in a small bowl, stir together sour cream, lime rind and lime juice.
Divide beef-veggie mixture among tortillas and top with lime sour cream.