To add Vegetables at the end of Cooking:
Omit the vegetables at the beginning of preparation.
a) Cook the chicken and pineapple in the slow cooker with the sauce as directed. Add the vegetables during the last 1 hour of cooking. Thicken the sauce with cornstarch and water per the recipe, before serving.
b) Alternatively, stir-fry the bell peppers and onion in a couple of drizzles of oil in a skillet on the stove-top. Season with salt & black pepper to your taste. Thicken the sauce in the slow cooker per the recipe, then stir in crisp-cooked vegetables just before serving.
Chinese 5-Spice powder includes; cinnamon, fennel, schezwan peppers, star anise and clove ground into a spice blend. It's readily available on the spice aisle or in the Asian section of most grocery stores.