Mix meatball ingredients. Form meatballs and set them aside.
In a bowl, mix sauce ingredients: broth, tomato paste, mustard, Worcestershire sauce, garlic powder, and cornstarch. Set aside.
Cook meatballs in 1 tablespoon of oil and 2 tablespoons of butter until browned on all sides. Remove from the pan. Drain most of the fat.
Melt 2 tablespoons of butter in a pan and add onions. Cook until tender. Deglaze with the wine. Add gravy mixture and cook for several minutes until it thickens.
Swirl in 2 tablespoons of butter and then taste and adjust for salt, if necessary. Add meatballs and cook for a couple of minutes. Top with parsley. Serve with mashed potatoes and peas.