In a medium bowl, combine chicken, cheese, barbecue sauce, green pepper, and onions, stirring to combine.
Spread 1/4 of the chicken mixture (about 2/3 cup) down the center of each tortilla. Microwave just until hot and melty. (In our microwave oven, that's about 45 seconds, but microwave ovens vary in wattage, so adjust the time a little as needed.)
Sprinkle 1 tablespoon tomato on top of the warmed chicken mixture for each wrap, and then top each with a lettuce leaf.
Wrap up and serve while still warm.
Rotisserie chicken: As we mentioned in the post, rotisserie chicken is a quick, easy option for this recipe. But, nearly any boneless, skinless chicken breasts will also work well here, as long as they’re not seasoned with spices or marinades that compete with the other flavors in this recipe. If you prefer, you can simply plan on cooking a couple of extra chicken breasts whenever you’re making chicken, so you'll have extra cooked chicken for this recipe without any extra work.
Barbecue sauce: After testing various brands, we liked Stubb's Original in this recipe. Feel free to use your own favorite (we recommend sticking with "original" or "classic" flavors). Also, be sure to read ingredient labels carefully, as many sauces contain unexpected and undesirable ingredients, such as high-fructose corn syrup (at least one popular grocery store brand even lists it as the very first ingredient).
Make-ahead steps and meal prep: You can shred the chicken and chop the peppers and onions ahead of time. Or, you can go even further, and mix together the chicken, cheese, barbecue sauce, green pepper, and onions – then refrigerate (for up to about 3-4 days) until you're ready to make your wraps. This is great for meal prep, since you can make just one wrap at a time as needed, or an entire meal.