1 lb (500 g) continental lentils
1 green celery stalk
1 large clove garlic
3 or 4 sage leaves
4 tinned anchovy fillets
1 x 14 oz (400 g) tin tomatoes
4 thick slices bread, baked until crisp
(100 g) grated hard cheese
2 tbsp extra-virgin olive oil
1/2 oz butter
1. Place the lentils in a sieve and rinse very thoroughly under running cold water; leave to soak in a bowl of cold water for 1 hour. Heat 3 1/2 pints (2 litres) water in a large, heavy-bottomed flameproof casserole dish and as soon as it reaches boiling point, add the lentils. Boil them gently for 1 hour.
2. While they are cooking, finely chop the celery, garlic and sage and fry gently in the oil and butter for 10 minutes over a very low heat, stirring frequently. Remove from the heat, add the anchovy fillets and crush them into the oil and butter, using the back of a wooden spoon.
3. Return the frying pan to a low heat when they have broken up. Add the tomatoes and cook uncovered for 5 minutes, stirring to reduce and thicken.
4. When the lentils are tender, use a ladle to remove approx. 12 fl oz (350 ml) of the cooking liquid from the casserole dish.
5. Stir the tomato mixture into the lentils and allow to return to a very gentle boil. Add a little salt to taste.
6. Place the crisp, dry bread slices in the bottom of the soup bowls and sprinkle the cheese over them; ladle in the soup and serve immediately.