Königsberger Klopse

Name: 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 and 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