Firstly warm the oil in a pan over a low heat. Fry the chopped onion for 2 minutes, then add garlic and chilli until the onion is soft and slightly browned. Now pour in the Worcester Sauce, add chutney, chopped tomatoes, tomato paste, vinegar and brown sugar. Mix well and cook over a low heat until the sauce has reduced down to a jam-like consistency (about 15 to 20 minutes).
Remove from the heat and let the sauce cool down or fill immediately into jars.