1 large shallot, chopped 150g small cherry tomatoes, halved, or 3 medium tomatoes, deseeded and chopped 3 tbsp tomato ketchup 2 tbsp Worcestershire sauce 1 tbsp grain mustard juice of 1/2 lemon 1 tbsp balsamic vinegar 1 tbsp olive oil small handful tarragon leaves, finely chopped

Mix everything together. This can be done the day before, then kept covered in the fridge until required. Remove the sauce from the fridge at least 30 mins before serving.