Wash the chicken breasts and simmer in about 1 1/2 litres of water for about 1 hour. Onion wash, halve and cook. Skim broth from time to time. In the meantime peel kohlrabi and cut into small corners.
Clean and peel the carrots and cut them into slices about 1 cm thick. Clean the sugar snap peas and cut in half at an angle. Remove chicken breasts and onion from the stock. Season with salt and pepper. Add kohlrabi and carrots to the boiling broth and cook for about 5 minutes.
In the meantime, remove chicken meat from skin and bone and cut into slices. Add sugar snap peas to the soup. Stir in mashed potatoes. Warm the chicken meat in the boiling soup for about 1 minute.
Serve in a soup bowl with chervil and possibly sprinkled with pink berries.