In a large bowl, combine the orange juice, vinegar, garlic and seasonings; add the beef. Turn to coat; set aside. In a skillet, saute onion and peppers in 1 tablespoon oil until crisp-tender; remove and set aside., Drain and discard marinade. In the same skillet, cook beef in remaining 1 tablespoon oil until it reaches desired doneness, 2-4 minutes. Return vegetables to pan; heat through. Spoon meat and vegetables onto tortillas. If desired, top with cheese and serve with picante sauce and sour cream.