In a large mixing bowl combine the first eight ingredients and let sit for 5 minutes. Add ground beef and pork and mix just until combined. Form into 1 inch meatballs and place in hot skillet with olive oil. Fry on all sides until cooked through (about 10-15 minutes).
Remove from skillet and cover loosely with foil to keep warm, set aside.
Melt the 2 tablespoons of butter in the same skillet over medium to medium low heat. Whisk in the flour and cook for 1 minute. Slowly whisk in the beef broth scraping up the bits stuck at the bottom of the pan (there's a lot of flavor there!).
Reduce heat to a simmer and stir in the sour cream. Add meatballs and simmer covered for 5 minutes.