Soak the lentils in plenty of water for 2 hours. Rince and put lentils and bay leaves with plenty of water on stove to boil and cook for 45 minutes - lentils need to be well covered by water.
Meanwhile, fry the bacon until translucent, lightly browned, add the onions, leeks and carrots and cook until soft.
Add the flour and butter to the bacon and vegetable mix and cook until flour is deeply browned - not burned!
Then add the cooked and drained lentils to the bacon and vegetable mix and stir well to mix. Add the broth and vinegar and cook thoroughly until very thick. Season with salt and pepper.
Serve with Spaetzle (recipe below) and sausages/hotdogs and/or with a thick slab of bacon (feel free to cook together with lentils for a short time).