Wash potatoes thoroughly and cook in boiling water for about 20 minutes. Boil 4 eggs in boiling water for about 10 minutes until hard. Quench cold and peel. Halve eggs, remove egg yolks and pass through a fine sieve.
Season and mix with salt, pepper and mustard. Let the oil run in while stirring. Stir in sour cream and sour cream. Wash herbs, shake dry and remove coarse stalks. Chop herbs finely except for something to garnish.
Cut the egg white into thin strips. Add herbs and egg white to the sauce and season with salt and pepper. Meanwhile boil 10 eggs in boiling water for about 10 minutes until hard. Rinse cold, peel and halve.
Drain the potatoes, arrange on plates with eggs and sauce. Garnish with chervil.