6 oz (175g) dried butter beans
2 carrots
2 medium-sized potatoes
2 stalks celery
1 large onion
2 oz (50g) butter
21/2 pints (1.5 litres) water 1 chicken stock cube
1 bay leaf
1 tablespoon concentrated tomato puree
salt and freshly milled pepper
Soak the butter beans overnight and drain. Peel and chop the carrots. Peel and cut the potatoes in even-sized chunks. Trim and coarsely chop the celery. Peel and finely chop the onion. Melt the butter in a large saucepan over low heat, add the onion and fry gently for 5 minutes to soften but not brown. Add the prepared vegetables to the pan and toss them in the hot butter and onions.
Add the butter beans and pour in the water. Crumble the stock cube into the pan, add the bay leaf and tomato puree and season with salt and pepper. Bring to the boil, then lower the heat and simmer gently, covered, for 1 hour, until beans are tender. (Test by biting a bean — they can have a hard centre even when they feel soft on the outside.) Discard the bay leaf and pass soup mixture through a food mill, or puree in an electric blender or food processor. Return the soup to the rinsed pan. Reheat and check seasoning. Serve with fried croutons sprinkled on top.