Make the dressing: take a bowl and add mayo, 1 chopped cucumber, 2-3 chopped reddish, 1 chopped boiled egg, some chopped dill and spring onion. Mix all the ingredients well.
Chop some pickled herring and add to your dressing, or easily use them as they are.
Take a slice of dark rye bread and start layering. Pour some dressing, top some chopped herring and 2 or 3 pickled herring. Garnish with a piece of boiled egg, some slices of cucumber, dill, or slices of lemon.