Flatten the steaks with a meat hammer or rolling pin and cut into strips.
Mix the beef strips with the oil and fajita seasoning and set aside to marinate for 1 hour.
Heat a wide pan until very hot then add the beef, onion and sliced peppers and cook, stirring all the time, for 5 minutes then stir in the lime juice.
Place the beef mixture on the tortilla wraps, drizzle over a the sour cream and roll up. Garnish with a little cayenne pepper and serve with chilli sauce.