Rinse and drain the lenses. Peel and wash the carrots, cut them in half lengthwise and slice them. Clean, wash and halve the tomatoes. Clean the leek, cut into halves lengthwise, wash and cut into strips.
Cut the sausages into slices. Peel onion and cut into strips. Heat 1 tablespoon of oil in a large frying pan. Fry the sausage and carrots for 3-4 minutes, turning them over and taking them out. Add onion, tomatoes and leek to the hot frying fat and fry for 2-3 minutes.
Season vegetables with salt and pepper, remove. Dissolve frying set with 600 ml water, stir in lentils and cook covered for approx. 30 minutes until firm to the bite. In the meantime, pour on some water if necessary. Wash sage, dab dry, pluck leaves from the stems and chop coarsely.
When the lentils are cooked, add the sausage, sage, 2 tbsp. oil, vegetable stock and fried vegetables. Simmer for 4-5 minutes, turning. Season to taste with salt, pepper, sugar and vinegar.