Wash the potatoes and cook in boiling water for 15-20 minutes. Then rinse, peel and let them cool down. Meanwhile, cover the lentils and cook in salted water for 8-10 minutes. Cut potatoes into slices. Peel onions, dice finely and fry in hot oil.
Deglaze with 1/4 litre water and vinegar. Season well with stock, salt and pepper. Pour hot marinade over the potatoes and leave to stand for about 30 minutes. Peel the cucumber and cut into fine slices. Clean, wash and cut the bell peppers into pieces. Coarsely chop the feta cheese. Mix approx. 2/3 cheese and sour cream. Mix with cucumber, paprika and lentils into the potatoes. Leave to stand for about 1 hour. Clean and wash the romaine lettuce and cut it into coarse strips.
Coarsely chop the feta cheese. Mix approx. 2/3 cheese and sour cream. Mix with cucumber, paprika and lentils into the potatoes. Leave to stand for about 1 hour. Clean and wash the romaine lettuce and cut it into coarse strips. Fold into the potato salad and season to taste again if necessary. Arrange and sprinkle with the remaining feta cheese
waiting time approx. 2 hours