TO MAKE THE MEATBALLS:
Mix the first 10 meatball ingredients together in a large bowl.
Make golf ball size meatballs with the ground beef mixture.
Heat a large skillet over medium/high heat. Add the butter and oil and brown the meatballs on all sides. Remove the browned meatballs to a plate.
TO MAKE THE SAUCE:
Add the mushrooms and onions to the same skillet and saute for 3-4 minutes.
Add the beef stock, cream of mushroom soup, apple cider vinegar, caraway seeds, sour cream, and salt and pepper. Stir to combine.
Reduce the heat to low and add the meatballs back into the skillet turning them in the sauce coat.
Cover the skillet and simmer the meatballs in the sauce for 15 minutes on low.
To serve, spoon the sauce over the meatballs and garnish with chopped fresh parsley if desired.
Serve the meatballs over egg noodles, rice, or potatoes if desired. Or serve them as you would a meatball sandwich on a hoagie roll.