Vegetarian lentil soup

250 g lentils
2 litres water
1 large onion, chopped
2 large carrots, sliced
2 ribs celery, sliced
2 cloves garlic
5 T olive oil
2 or 3 tomatoes, peeled and diced (or 3 Tablespoons tomato puree)
2 bay leaves
oregano, salt & pepper
wine vinegar (optional)

Rinse the lentils well and boil them in plenty of water for a few minutes. Drain them and discard this first cooking water (Greeks do this with almost all pulses, they are more digestible this way). Bring them to the boil again in the 2 litres of water with the onion, carrot, celery, garlic, olive oil, tomatoes and bay leaves. Simmer for about 1 hour.
Season to taste with oregano, salt and pepper, adding a bit of wine vinegar, if wished.
Serve with raw cabbage and or carrot salad, tsatsiki and/or feta cheese.