In a large skillet over medium heat, melt butter.
Sprinkle flour over melted butter and whisk until smooth. Cook for a minute or 2 until it turns golden brown.
Slowly add the beef broth while whisking until well blended.
Add the soy sauce, Worcestershire sauce, and meatballs to the mixture and cook the gravy while stirring with a spoon until it thickens, about 5 minutes or so.
Add frozen veggies to the gravy and cook for 2-3 minutes until heated through. Serve over mashed potatoes.