Set aside 2 tablespoons toasted sesame seeds for Sesame-Sour Cream Sauce. Cut bread slice into quarters. Process bread quarters in food processor or blender until fine crumbs form. Crumbs should measure 1/2 cup.

Combine ground beef, onion, bread crumbs, egg, milk, salt, pepper and ginger in large bowl.

Place meat mixture on cutting board; pat evenly into 8X6-inch rectangle. With sharp knife, cut meat into 48 (1-inch) squares; shape each square into 1-inch meatball.

Heat 2 tablespoons oil and 2 tablespoons butter in large skillet over medium heat. Cook half of meatballs until brown on all sides, 8 to 9 minutes. Add 1/2 cup broth. Bring to a boil. Reduce heat to low. Simmer, covered, 5 to 10 minutes. Set cooked meatballs aside. Repeat with remaining meatballs, using remaining 2 tablespoons oil, 2 tablespoons butter and 1/2 cup broth.

Meanwhile, prepare Sesame-Sour Cream Sauce. Place hot meatballs in serving bowl; top with sauce. Sprinkle with the remaining 2 tablespoons toasted sesame seeds. Garnish, if desired.

Melt butter in small saucepan over low heat. Blend in flour, ginger and salt. Cook and stir until bubbly, about 1 minute. Add beef broth. Cook until thickened, stirring constantly, for an additional minute. Add soy sauce and sesame seeds.

Remove from heat; pour into small bowl. Add sour cream, stirring until smooth.