Peel, wash and cut the kohlrabi into 5 slices. Cook in salted water for about 5 minutes. Drain and let cool.
Wash the tomatoes, cut them in half. Peel onion and cut into strips. Cut avocado in half, remove seeds, peel flesh and dice. Mix with tomatoes and onion. Season to taste with salt, pepper and lemon juice. Peel garlic and chop finely. Mix yoghurt and garlic, season with salt.
Crush cornflakes finely and mix with breadcrumbs. Whisk eggs, salt and pepper. Turn kohlrabi first in flour, then in egg and finally in cornflakes. Fry in hot oil in portions on each side for about 2 minutes. Serve with avocadosalsa and aioli.