Shape the meat mixture into 1 1/2-inch meatballs and place them on a plate. Chill the meatballs in the refrigerator for about 15 minutes to help them hold their shape.
Heat the remaining tablespoon of olive oil in the skillet over medium-high heat. Brown the meatballs in batches, about 1 minute per side, until they are evenly browned.
Stir in the flour and cook for 2 minutes while stirring constantly. Gradually whisk in the beef broth until the mixture is smooth. Add the Worcestershire sauce and Dijon mustard.