1. Pat the steaks dry with paper towels and place in a heavy duty resealable plastic bag. Juice the orange and lime. Finely chop the garlic. Combine the juices and garlic with Worcestershire sauce and oil and pour over the meat. Seal and place on a baking sheet to marinate at room temperature for 2 hours.
2. Remove the steaks from the marinade, pat dry, and season with salt (in moderation) and pepper. Heat a gas or charcoal grill to high. Grill steaks 5 min., flip, and grill an additional 3-5 minutes, or until they reach 135°F on an instant read thermometer for medium rare. Remove steaks from the grill, cover with foil, and allow to rest 5 minutes.
3. While steaks rest, place the onions and peppers in a disposable perforated foil grill pan. Grill 4 minutes, stirring frequently, adding the jalapeños for the final minute.
4. Warm tortillas on the grill, about 1 minute. Cut the meat into thin strips. Top tortillas with meat, vegetables and sour cream.
Per serving: 588 calories, 35g fat, 12g saturated fat, 85mg cholesterol, 443mg sodium, 42g carbohydrate,5 g fiber, 7g sugar, 28g protein