Bring the lentils in the vegetable stock to a boil in a small saucepan. Simmer over low heat for 4 minutes. Now take the pot off the stove and let the lentils cool down a little. Stir in the oil and vinegar. Season to taste with the spices.
Wash the lamb`s lettuce and pluck the leaves off. Mix the leaves in a bowl with the chopped walnuts. Peel, core and cut the apple. Mix with the salad. Finally, carefully fold in the lukewarm dressing and serve immediately.
If you want to serve the salad cold, let the dressing cool completely before adding it to the salad.