Wash, peel and chop the greens and potatoes, dice the onion. Heat the oil in a pan, sauté the onion, add the vegetables and sauté briefly.
Season with salt and pepper and pour in the soup. Simmer for approx. 20 minutes. Drain the lentils in a sieve and rinse thoroughly under running water. Leave to drain.
Add to the vegetables in the pot 5 minutes before the end of the cooking time.
Serve garnished with parsley.