In a large bowl, combine the 2 tablespoons barbecue sauce and tomato paste with the garlic powder, stock powder and salt. Mix well. Add the chicken pieces and mix again until chicken is evenly coated. Set aside. (Chicken can be marinaded for a couple hours; overnight; or cooked straight away, depending on the depth of flavour you like).
Preheat a nonstick pan/skillet on medium heat, and spray with a little cooking oil. Fry onion slices until transparent. Add the chicken and fry, stirring once, for a couple of minutes until the underside is golden and slightly crisped. Flip the chicken pieces with a spatula and cook the other side until cooked through.
Divide all ingredients in half to prepare both wraps. Place onto the side of each wrap: avocado slices, chicken pieces, olives, pineapple chunks, tomato slices, herbs and cheese. Drizzle with a little extra barbecue sauce. Fold empty side of wrap over the cheese to cover, and place onto a separate preheated pan or sandwich press sprayed with a tiny amount of cooking oil. Cook on low-medium heat until wrap is golden. Flip with a spatula and cook the other side until cheese has melted through and wrap is completely cooked.