In a large, deep skillet, cook the bacon over medium heat until browned. Remove with a slotted spoon and pour out all but one tablespoon of the fat.
Cook the chopped onion until browned, about 5 minutes.
In a large bowl, use your hands to combine the ground beef with the bacon, onion, egg, bread crumbs, garlic, Worcestershire sauce, spices, salt and pepper. Do not over-mix.
Roll the meat mixture into meatballs of any size. I do about 1.5 inch meatballs, but mini ones are fun too.
Heat the same skillet again over medium heat and cook the meatballs, turning periodically until browned on all sides. Work in batches if necessary. Remove the meatballs and set aside.
Sauce
Melt the butter in the same skillet, and add the flour, stirring continuously until lightly browned.
Add the beef broth and stir, scraping up the browned bits with a wooden spoon. Cook for a few minutes.
Mix in sour cream, Worcestershire sauce, and dijon mustard. Simmer until sauce is thickened. Taste and add salt and pepper as desired. Add the meatballs back to the pan to cook through (3-5 minutes).
Serve over egg noodles or mashed potatoes, garnished with chopped parsley if desired.