Prepare the lentils according to the package instructions. E.g. soak the pardine lentils overnight, pour them into a sieve and rinse. Simmer in unsalted water for about 10 minutes, drain well in a sieve and allow to cool.
For the dressing, mix well oil, vinegar, salt, pepper and 1 - 2 tablespoons of jelly or mix in a shaker.
Eighth the apple, remove the core and cut across into thin slices. Put the apple pieces in the salad bowl and mix with the lemon juice.
Clean the fennel, pluck the leaves from the stalks and roughly chop. Quarter or eighth of the fennel bulb, remove the hard stalk and cut the fennel diagonally into thin slices.
Peel and quarter the cucumber and cut into thin slices. Clean the celery, coarsely cut the leaves, cut the celery stalks and spring onions into slices.
Add everything to the apples and mix well with the dressing. Fold in the lentils last.
Let the salad sit for about 4 hours, mixing it from time to time. If necessary, add a little more seasoning.