Mum's barbecue sauce (good on baked fish)

2 onions
2 tbsp diced celery
2 tbsp vegetable oil
8oz tomatoes
1 level tbsp tomato puree
4 teaspoons soft brown sugar
2 level teaspoons mustard
1 tablespoon worcester sauce
2 teaspoons lemon juice

Cook the onions and celery off til they're soft, add everything else and simmer for a few minutes, then slather over whatever meat or fish you're grilling and Bob, as they say, is your uncle. Except my uncles are called Brian, John, Michael and David.