Simple Sweet and Sour Chicken

4 boneless skinless chicken breasts , cut into 1in cubes

1 small red pepper, de-seeded and cut into 1 small green pepper , de-seeded and cut into 1 tablespoon fresh ginger , peeled and finely chopped

6 garlic cloves , chopped

1 (8 ounce) can water chestnuts , drained and sliced

1 bunch scallion , cut into 1in pieces

1 (8 ounce) can pineapple slices , drained and cut into chunks

white pepper

1 tablespoon soft light brown sugar

2 tablespoons rice vinegar

3 tablespoons rice wine or 3 tablespoons dry sherry

2 tablespoons dark soy sauce

3/4 cup chicken stock

2 tablespoons tomato paste

2 tablespoons cornflour , mixed with

2 tablespoons water