here's the tried and tested:
small oinion, chopped
green pepper, diced
1oz plain flour
1 Tbsp mango chutney
2 Tbsp malt vinegar
2 Tbsp soft brown sugar
1 Tbasp tomato puree
2 tsp worcester sauce
8oz can of pineapple pieces
½ pint stock
fry onion and pepper for 5 mins or until almost tender
stir in flour and cook for a minute
add chutney, vinegar, sugar, tomato puree, worcester sauce, pineapple, stock and stir
Bring to the boil, cover and simmer for 10-15 mins
Voila!
The other, which I haven't tried is:
2½ Tbsp sugar
2 Tbsp wine vinegar
1½ Tbsp cornflour mixed into 8-12 Tbsp water
1½ Tbsp soy sauce
1 Tbs dry sherry
1½ Tbsp tomato puree
2 Tbsp orange juice
1 green or red pepper cut into thin strips
1 onion, finely chopped.
Stir fry onion and pepper for 2 minutes
Add all other incredients and stir constantly over a low heat until thickened.