Sauté the root vegetables with the potatoes in vegetable oil, rinse the lentils and add them. Add the clear soup and bring to a boil. Squeeze the garlic clove smooth and add it. Gently simmer the stew at low temperature, season strongly with salt and freshly ground pepper and dilute with the water to the desired consistency.
The lentils are perfect when they still have a slight bite. Bring to the table in a deep dish and sprinkle with fresh chopped parsley.