Put the sultanas, garlic, chillies, vinegar and tomatoes (with their liquid) in a saucepan with the sunflower oil. Bring to the boil, lower the heat and simmer gently for 15 minutes.
Add the tomato ketchup, simmer for another 5 minutes, then transfer to a food processor. Season with the salt and pepper, and whiz to a purée.
Taste and adjust the seasoning if desired. If it is not