Put a 400g can chopped tomatoes, 1 finely chopped red chilli, 1 grated thumb-sized piece of ginger, 1 star anise, 250g caster sugar, 150ml red wine vinegar and a pinch of salt in a pan. Bring to a simmer and cook for 30 mins until thick and glossy. Remove from the heat, leave to cool, and transfer to a sterilised jar. Will keep for two weeks, or unopened for up to six months.