Meanwhile, finely chop the onions and fry them in the margarine until translucent. Add the corned beef and fry with it.
Drain the potato water, add the corned beef with the onions to the potatoes and mash to a coarse pulp. Season to taste with a little cucumber water, salt and pepper.
Fry the two eggs into fried eggs.
Arrange the Labskaus on plates and serve with a fried egg, 1 fish, 1 cucumber and a few slices of beetroot.
By the way, Labskaus tastes best the next day. Fry lightly in a pan with a little fat. The Labskaus can also be frozen without any problems.