Shape the ground beef into an oval patty about 1/2 to 3/4 inch thick.
Put in the center of a serving plate. Score surface in a diamond pattern by pressing with edge of a knife, then top with 3 or 4 diagonally placed bands of the caviar.
Surround the beef with chopped onion and garnish with sprigs of parsley.
Spread on buffet-style rye bread.