Diet Cola Chicken

Name: Diet Cola Chicken
Ingredients: 1 tbsp vegetable oil; 4 chicken breasts, cut into bitesized chunks; 1 red bell pepper, cut into large chunks; 1 yellow bell pepper, cut into large chunks; 1 green bell pepper, cut into large chunks; 1 onion, peeled and finely chopped; 2 cloves garlic, peeled and finely chopped; 1 x 330ml can diet cola; 8 tbsps passata; 4 tbsps tomato puree; 200ml hot chicken stock made with 1 stock cube; 1 tbsp Worcestershire sauce; 1 tbsp dark soy sauce; 1 tbsp dried mixed herbs; 200g sugar snap peas