combine the chicken and taco sauce in a medium bowl. Cover with plastic wrap and place in the fridge for 5-10 minutes to marinate.
heat the oil in a large frying pan over medium heat. Add the onion and zucchini and cook, stirring, for 5 minutes or until the onion begins to brown. Add the capsicum, mushroom and sugar. Cook, stirring, for 5 minutes or until the sugar dissolves and begins to caramelise.
meanwhile, heat a large non-stick frying pan over high heat. Add the chicken mixture and cook, stirring occasionally, for 10 minutes or until cooked through.
place the refried beans in a small saucepan over low heat and cook, stirring, for 5 minutes or until heated through.
top the tortilla wraps with the onion mixture and the chicken mixture. Serve with sour cream and refried beans.