Steak fajitas! Any tips ?
I don't recommend marinating for more than a few minutes, even less. You should be using a thin cut of steak, such as flank steak or skirt steak. Sear it on a red hot pan, or grill over direct heat, rest and cut across the grain.
Here's a very enlightening article about marinades called The Myth About Marinades, which dispels common misconceptions about marinating meat, including the need to marinate for more than a few seconds.
A couple of things that I believe make or break steak fajitas.
Marinade (garlic paste or crushed garlic, lime juice, cumin, olive oil. Marinate in refrigerator minimum of two hours - overnight preferred.
Grilled steak. Charcoal grilling makes all the difference..
Julienne peppers (multiple colors)
Julienne onions sliced with the grain
Grill peppers and onions (optional)