Place the bread in a food processor or mini chopper and blitz until it becomes fine breadcrumbs. Alternatively, you can use a coarse grater to make the breadcrumbs.
Place the breadcrumbs in a medium bowl with the turkey mince, garlic, root ginger, spring onion, Chinese five spice powder and egg. Season well with salt and pepper.
Using clean hands, mix the turkey mixture until well combined and divide into 12 equal pieces. Shape into 12 balls and set aside.
For the sauce: spray a large frying pan with low-calorie cooking spray and place over a medium heat. Add the red pepper, green pepper, garlic and chilli and fry for 5 minutes, stirring, until just beginning to soften.
Add the meatballs and seal on all sides for about 5 minutes, turning them carefully, until lightly browned all over.
In a small bowl, mix the peanut butter powder with 2 tbsp water until smooth. Stir in the soy sauce, sweetener, rice wine vinegar and 400ml water.
Tip the sauce mixture into the frying pan with the meatballs and simmer, uncovered, over a low heat for 15-20 minutes. Turn the meatballs occasionally and make sure there are no signs of pinkness after cooking.
Blend the cornflour with 2 tbsp water until smooth. Pour into the sauce in the frying pan and stir in. Simmer for 5 minutes until the sauce has thickened.
Sprinkle with chopped spring onion and serve with Basmati rice or noodles.