Peel and wash the celery, carrots and parsley root. Dice celery and parsley root. Cut carrots into slices. Clean, wash and cut leek into thick rings. Peel onions and garlic.
Cut onions into slices, chop garlic finely. Wash parsley, dab dry and chop, except for a little bit for garnishing. Wash the meat and dab dry. Season with salt and pepper. Heat 2 tablespoons of oil in a large frying pan.
Fry the escalopes in portions for 4-5 minutes, turning them over. Meanwhile cook celery in boiling salted water for about 5 minutes. Add leek and carrots 3 minutes before the end of cooking time. Pour the vegetables into a sieve and quench.
Heat 1-2 tablespoons of oil in a frying pan and fry the vegetables for about 3 minutes, turning them gently. Season with salt, pepper, sugar, lemon juice and zest. Mix in parsley and butter. Arrange the vegetables and schnitzel on a plate, ciabatta bread tastes good with them.