Cut the leek, carrots and celeriac into fine cubes. Put the cloves in the peeled onions.
First sauté the onions and bacon in a saucepan with oil, then add the diced vegetables.
Then add the lentils and bay leaves and sauté briefly. Season lightly with salt, pepper and nutmeg. Then add the stock and simmer gently with the lid closed until the lentils are soft (they can be al dente).
Melt the butter in a small, second saucepan and then add the flour. Simmer the roux until it is dark brown (be courageous - this creates flavor). Then stir the roux with a ladle of broth and then add to the saucepan with the lentils. Let it simmer again briefly. Season to taste with vinegar, salt and pepper.
The lentils taste best with Viennese (strings) and homemade spaetzle.