Sill. One element present in most of the smörgåsbord served in Sweden is the country’s favorite when it comes to seafood. The Pickled Herring (Sill) is a basic ingredient of the typical Swedish buffet. The Swedes have been pickling herrings since the Middle Ages when this fish was abundant & pickling was the best way of preserving the fish. You’ll be surprised to find that pickled herrings come in a variety of flavors like mustard, onion & garlic & are usually eaten with boiled potatoes crispbread & hard-boiled eggs.