1 - Put the oil, onions, celery, carrots, potatoes and bay leaves in a big casserole dish, or two saucepans.

2 - Fry gently until the onions are softened – about 10-15 mins.

3 - Fill the kettle and boil it.

4 - Stir in the tomato purée, sugar, vinegar, chopped tomatoes and passata, then crumble in the stock cubes.

5 - Add 1 litre boiling water and bring to a simmer.