Königsberger Klopse

Ingredients

• 2 kaiser rolls, torn into 1/2-inch pieces
• 4 cups beef broth
• 1 cup sour cream
• 2 large egg yolks
• 2 anchovy fillets, rinsed and minced
• 2 pounds meatloaf mix
• 1 small onion, chopped fine
• 3 tablespoons capers, rinsed and chopped
• 3 tablespoons minced fresh parsley
• Salt
• pepper
• 1 teaspoon ground allspice
• 1/2 teaspoon ground nutmeg
• 5 tablespoons unsalted butter
• 1/2 cup all-purpose flour
• 2 cups water
• 1 bay leaf
• 1 sprig fresh thyme
• 2 tablespoons Worcestershire sauce
• 1 teaspoon grated lemon zest