Mix meat, grated onion, bread crumbs, salt, pepper and nutmeg.
Add stiffly beaten egg whites last. Form into balls.
To make sauce, boil water, onion, bay leaves, sugar, salt and allspice and peppercorns
mixture for 30 minutes. strain; bring to boiling point.
Add meat balls and simmer for 15 minutes.
Remove meat balls to hot platter, keeping them hot. Add vinegar to liquid.
Dissolve flour in small amount of cold water. Add to beaten yolks. Add this thickening mixture
gradually to seasoned liquid, stirring constantly until smooth and thick. Pour over
meat balls, and garnish with lemon slices and capers.