Kung Pao Chicken


3 large skinless chicken breast fillets, cut into bite-sized pieces
4 tbsp white wine vinegar
6 tbsp soy sauce
6 dried red chilies, broken into 1in lengths and seeds shaken out
2 tsp Szechuan peppercorns, lightly crushed
2 tbsp sweetner
3 tbsp tomato paste
10 fl oz chicken stock
Low calorie cooking spray
8 scallions/spring onions, diagonally cut into 1inch lengths
3 garlic cloves, peeled and crushed
1 red bell pepper, deseeded and roughly chopped
2 x 8oz cans bamboo shoots, drained
2 x 8oz cans water chestnuts, drained
Salt and freshly ground black pepper
3½ baby spinach leaves