Papasitos Fajita Marinade:Don't over marinate. Part of why Papasitos are so good is they still taste like beef. 4-6 hours max. Overnight is wayyyyy too long -Use loin flap instead of skirt steak. You can buy it at Costco. It's very similar to skirt, but, slightly thicker and much less connective tissue - Don't cook past medium doneness WARNING: try them this way and you'll never want the pre-marinated garbage again!