I want to add fajitas to my menu. However I have never bought them, never grilled them, I don't know zip about them. Do i buy them pre-marinated or not, if now with what and how do you season them and with what? Most of the ones I have had were OK, but I would like to know the full story on them. How to grill, how to serve, and portion size as well. Can anyone help me out?