Clean the lentils, place them in a bowl, cover them with cold water and soak for 12 hours. Peel the onions finely, clean the celery and chop it into chunks. then drain and rinse the lentils and place them in a pan, cover them with water, add the onion, the garlic, the bay leaf, the celery and gently bring to the boil then season with salt.Simmer over a low heat for an hour. If the lentils dry up too much add some warm water. Once cooked remove them from the heat, add other boiling water, bring to the boil again, toss the pasta in it and cook for about 10 minutes (the water must be completely absorbed).Once cooked, remove from the heat, sprinkle with olive oil and a grind of pepper, pour the lentils and the pasta in a soup tureen and serve.