Caviar Mousse

3 hard-boiled eggs
1/4 lb butter softened
1 medium onion, finely chopped
1 cup sour cream
6 ounces black caviar
Melba Toast

Blend the eggs with the butter in a food processor. Spread the egg-butter mixture in a small serving bowl. Mix onion with sour cream and spoon over egg mixture. Refrigerate overnight. To serve, top with caviar and pass with Melba toast.