Roughly chop the onion, celery stalks and carrots into smallish pieces.
Heat the oil in a saucepan. Fry the onions and garlic for 1-2 minutes, then add celery and carrot.
Sauté the vegetables under cover for about 10 minutes or until the vegetables are tender .
Meanwhile, wash the lentils thoroughly. When the vegetables are softened, add the lentils, stir, then pour in the water and add the bay leaf. Season to taste.
Bring to the boil, then simmer for 30 minutes under cover.
When the lentils are soft and mushy take out the bay leaf, then blend to a creamy soup.
Scatter some chopped parsley on top and serve with crusty bread.