How to Make It
Heat oil in a large skillet over medium-high heat. Add mushrooms and next 7 ingredients (mushrooms through ground round); sauté 5 minutes until meat is browned, stirring to crumble. Stir in ketchup and next 6 ingredients (ketchup through tomato sauce); bring to a boil. Cover, reduce heat, and simmer 20 minutes, stirring occasionally. Serve on toasted hamburger buns.