This dish is very popular in Russia. I, as a Russian native, do it almost in the same way, except that I do potato as the first layer and I don't top the dish with the grated hardboiled egg, but with medium chopped pieces of pecans instead. Chopped onions go great with herring, so I always put them in. Be careful as not to put much mayonnaise between the layers, especially since there is a thick layer on top. Also, I prepare the dish on a large flat plate - that way, when cutting a piece off of the whole pie (it looks like a pie), you are ensuring a nicely preserved piece of layers. I wouldn't prepare it in a deep bowl.