Prepare the mountain lentils according to the instructions on the package. Peel the potatoes and carrots, cut into cubes and cook for about 20 minutes.
Peel the apples, cut into cubes and fry them together with the onions in olive oil, briefly toast the nuts.
Mash the lentils, potatoes and carrots and season with salt, vinegar, salt and pepper. Mix in the apple pulp and the apple-nut mixture and season if necessary.