You either take a larger bowl and make several layers or smaller, flatter bowls.
Cut the herring into small pieces and lay them out at the bottom of the bowl. Scatter chopped onions on top, rub boiled eggs with a grater, rub boiled, peeled potatoes on top. Press everything down carefully.
If only one layer is made, rub the beetroot over it, press it down and coat with mayonnaise. If several layers are made, the potatoes are followed by a thin layer of mayonnaise and then again herring, etc.