Quarter the lettuce heart and cut into strips. Quarter the tomatoes, remove the core and cut the pulp into strips. Cut the cleaned peppers into small pieces. Peel, halve, slice the kohlrabi and then cut into strips. Halve the schnitzel lengthways and cut into strips. Chop the onion into small cubes. Gently mix everything with the lentils.
Mix a dressing from oil, vinegar, herbs, salt, pepper and sugar and add to the salad. Mix in carefully and let the salad stand for half an hour before serving.