I'm going to try OldSchool's.
If you want simple, Penzey's make a good fajita seasoning, I think. Oil, lime juice, the seasoning, and water. Marinate up to overnite. I slice flank steak across the grain before marinating and grill the strips over hardwood charcoal so hot you need a LONG tongs. Cook for two to three minutes. Cilantro, guac, Anejo cheese crumbles, thin sliced sweet or red onions, Mexican crema if you want, fresh limes to squeeze over. Roasted poblano strips add some bearable spice. Soft fresh corn tortillas taste best, but flour work better for a crowd.
I've done this at Lambeau in the parking lot. Bring extra, because strangers will start milling around from the smell of the giant clouds of smoke. You might have to feed them to protect yourself.
Kevin
I like muskies.