Boil the eggs hard for about 10 minutes. Heat 1 tsp. oil in a frying pan. Fry the diced ham until crispy, take it out and let it drain on kitchen paper. Peel and finely dice the shallot
Mix sour cream, yoghurt, mustard and 2 tsp. oil. Stir in diced ham, except for something to sprinkle, and diced onion. Quench eggs in cold water, peel and chop. Finely chop the gherkins. Wash parsley, shake dry, pluck leaves from stalks except for some for garnishing and chop finely. Mix eggs, gherkins and parsley, except for a little bit for sprinkling, with the sour cream mixture. Season with salt, pepper and sugar
spread the egg mixture on the slices of bread, arrange on plates and sprinkle with parsley and diced ham