Boil eggs and potatoes, cool. Peel the herring from the skin and bones.
We will prepare the" highlight of the program " - fruit sauce.
Combine the ground berry with the mustard seeds and lemon juice (I needed 2 tsp), mix, add the remaining ingredients for the sauce.
Peel the cooled potatoes and eggs and cut them into slices, half-ring the onion, and coarsely chop the arugula. Cut the herring fillet into strips.
Combine everything in a salad bowl and season with the sauce. Let stand for 1 hour.