Soak the plate lentils in water for 1 to 2 hours. This is not necessary with the red lentils.
Then cut the potatoes, carrots, onions and the bacon into small cubes. Bring everything to a boil along with the vegetable stock. Add the vinegar and cook for about 1 hour.
Now cut the sausages into slices and add them. If the soup is too thick, add more water. Let everything simmer again for a good half an hour.
It is advisable to freeze a remainder, or to make double the amount in stock!