In a large bowl, mix together the meatball ingredients and form into 1 - 1 ½” sized balls. Set aside.
1 pound ground beef, 1 egg, 2 tablespoons onion, 1 tablespoon garlic powder, ½ cup panko breadcrumbs, 2 tablespoons Worcestershire sauce, 2 teaspoons kosher salt, 1 teaspoon black pepper
In a large skillet, heat the olive oil over medium high heat until hot and it begins to shimmer. Add the meatballs and saute, turning frequently, until golden brown on all sides. Remove to a plate lined with a paper towel.
4 tablespoons olive oil
While the sauce is being prepared, cook the egg noodles in salted water until done. Drain, then add butter and mix so they don’t stick together. Set aside until the sauce is ready.
1 pound wide egg noodles, 2 tablespoons unsalted butter
In the same pan used to cook the meatballs, saute the onions over medium high heat until translucent, about 7 to 8 minutes.
1 white onion
Add the mushrooms and cook for another 5 to 6 minutes until tender.
½ pound white button mushrooms
Sprinkle the flour over the onions and mushrooms, then stir together until well combined. Continue to cook for another minute.
2 tablespoons all purpose flour
Add the beef stock, mustard, salt and pepper. Return the meatballs to the pan. Cook for 8 to 10 minutes until the meatballs are cooked through and the sauce has thickened.
1 cup beef stock, 1 teaspoon wholegrain mustard, 2 teaspoons kosher salt, 1 teaspoon black pepper
Turn off the heat, add the sour cream and fresh parsley.
½ cup sour cream, 3 tablespoons fresh parsley
Serve over the buttered egg noodles.