Chicken fajita recipe, already cooked the chicken?

[LuvMeDontEatMeVEG]

HI, we have already cooked the chicken because we weren't sure what we were going to make with it yet. Does anyone have a recipe that uses chicken, some kind of taco seasoning, we also have onions, bell peppers, and mushrooms, cheese, lettuce, tomatoes, tortillas. The thing is, i am just not sure how to mix the chicken in with the sauteed peppers/onions etc, while adding in some Mexican food seasoning. Do i need some kind of liquid? The recipes i find online are all with raw chicken. Thank you! Your help is appreciated. =)