- 1 tablespoon butter
- 1 tablespoon olive oil
- 2/3 cup chopped onion
- 2 cloves garlic, chopped
- 2 tablespoons all-purpose flour
- 2/3 cup beef broth
- 1 cup Burgundy wine
- 1 pinch dried basil, or to taste
- 1 pinch dried oregano, or to taste
- 1 1/2 cups sliced baby portobello mushrooms
- Heat butter and olive oil in a large skillet over low heat; cook and stir onion and garlic in the hot butter-oil mixture until onion is transparent, 5 to 10 minutes. Add flour and slowly pour in beef broth while stirring constantly until flour is smoothly mixed into the broth and vegetables.
- Stir Burgundy wine into onion-flour mixture; season with basil and oregano. Bring mixture to a simmer; add mushrooms. Cook and stir until sauce is thickened, about 10 minutes.