Boil the eggs for about 7 minutes in boiling water until they are hard, then rinse with cold water. Cut gherkins into fine cubes. Peel and finely dice onion. Chop capers coarsely. Wash herbs and shake dry. Cut chives into fine rolls, chop parsley finely.
Peel eggs, chop finely. Mix eggs, gherkins, onion and herbs, except for some chives and 1 teaspoon gherkins for garnishing. Mix with mayonnaise, yoghurt and mustard. Season to taste with lemon juice, salt and pepper.
Sprinkle with the rest of the chives and cucumber.