- 12 ounces 90%-lean ground beef
- 1 large onion, finely diced
- 2 cups finely chopped cremini mushrooms
- 5 plum tomatoes, diced
- 2 tablespoons all-purpose flour
- 1/2 cup water
- 1/4 cup cider vinegar
- 1/4 cup chili sauce, such as Heinz
- 1/4 cup ketchup
- 8 whole-wheat hamburger buns, toasted if desired
- Crumble beef into a large nonstick skillet; cook over medium heat until it starts to sizzle, about 1 minute. Add onion and mushrooms and cook, stirring occasionally, breaking up the meat with a wooden spoon, until the vegetables are soft and the moisture has evaporated, 8 to 10 minutes.
- Add tomatoes and flour; stir to combine. Stir in water, vinegar, chili sauce and ketchup and bring to a simmer, stirring often. Reduce heat to a low simmer and cook, stirring occasionally, until the sauce is thickened and the onion is very tender, 8 to 10 minutes. Serve warm on buns.