Wash the lentils until the water runs clear. Sweat the onion and garlic in the oil and deglaze with the water.
Add the vegetable stock and the lentils. Bring to the boil briefly and then simmer for 15 minutes on a low level, stirring occasionally.
Remove from the plate, stir briefly, add the tomato paste and puree with a hand blender. Add the lemon juice, then season and season to taste. Serve with bread.