Recipe: Gefilte Fish

 To make the stock: Set whitefish fillets on a board, skin side down. Slip blade of a flexible knife between flesh and skin and use it to remove the skin, sliding the knife away from you with 1 hand and pulling skin off with the other. Run your fingers carefully over fish fillets and remove any remaining small bones. Set fillets aside. Rinse bones and heads of all fish under cold running water for 5 minutes. Combine fish bones and heads, onions, 1 teaspoon salt and water in a large, deep pot. Bring to a boil. Skim off foam as it accumulates. Cover and simmer for 30 minutes. Strain and return to pot. Taste for seasoning.

 To make the fish: Grind whitefish and halibut fillets in 2 batches in a food processor until fine. Return half the fish to food processor and add 1 egg, half the chopped onions, 1 teaspoon salt and 1/4 teaspoon pepper. Process to mix. Transfer to a large bowl. Repeat with remaining fish, egg, onion, salt and pepper. Add to the bowl and mix with first batch. Stir in matzo meal.

 Add carrots to strained stock and bring to a simmer. With moistened hands, shape fish mixture into balls, using 1/4 to 1/3 cup mixture for each. Carefully drop fish balls into simmering stock. If necessary, add more hot water so fish balls are covered. Bring to a simmer. Cover and simmer over low heat 1 hour. Let fish cool in stock. Chill fish with a little stock for at least 4 hours before serving. Chill carrots and remaining stock in separate containers.

To serve: Garnish each fish ball with a carrot slice. Pass horseradish and a little of the chilled stock separately.