Hard-boiled eggs, sour cream, and onion are traditional accompaniments for caviar. In this longtime staple of community cookbooks, they are turned into a shallow cake and spread with caviar. We used supermarket lumpfish caviar, but if you're feeling flush, use the good stuff, or even Japanese tobiko (flying-fish roe).
Cooks' note:
Draining the black lumpfish caviar removes excess fish ink, which stains the cream. This is not necessary for higher-quality caviar or tobiko. For a caviar alternative, try Cavi-art from caviart.us.