Put 1 cup of German lentils in a saucepan with 2 cups of cold water or vegetable stock, and let boil for an hour. If the water is absorbed before the lentils are tender, add a little more. At the end of the hour pour over them 6 cups of hot water or stock.
Put 1 tablespoon of butter in a frying pan, and when melted add 1 small onion chopped fine and 1 tablespoon of flour and 1 clove of garlic. When browned add this to the soup and at the same time put in ½ cup of diced potatoes. Let simmer gently for half an hour, then press through a sieve, return to the fire, season well with salt and pepper, and add 1 tablespoon of lemon juice or reduced vinegar before serving.
PURÉE MONGOLE
Put 1 can of tomatoes in a saucepan and with it 2 cups of strong vegetable broth, 1 stalk of celery, 1 slice of onion, 1 bay leaf, 3 allspice, 3 cloves, salt and pepper, and let cook slowly for half an hour. Pour the liquid through a sieve, pressing with it as much of the tomato as will go, reserving the celery. Return to the saucepan, add 1 tablespoon of reduced vinegar, 1 tablespoon of boiled peas, 1 tablespoon of canned string beans, split in half, and the cooked stalk of celery shredded into thin strips two inches long; let simmer for five minutes, season with salt and pepper, add 1 tablespoon of butter, remove from the fire, and beat vigorously into the soup 1 well-beaten egg.
MUSHROOM BISQUE
Cut up with a silvered knife about 1 cup of fresh mushrooms, wash and drain, toss about in 2 tablespoons of melted butter for ten minutes, then stir in 1 tablespoon of flour made smooth in a little milk, and add 1 quart of milk and let simmer half an hour. Season with salt and paprika, and press through a sieve, reserving half the mushrooms. Add these to the soup, and serve with croutons.