Hard boil the eggs. Mix the sour cream, creme fraiche, quark, oil and milk together. Season to taste with salt, pepper and mustard.
Dice the eggs and add the chopped herb mixture (e.g. parsley, dill, chives, cress, lemon balm depending on your taste) to the sour cream, creme fraiche and quark mixture.
You can just as well chop up an iceberg lettuce and fold it in.