Mushroom Gravy

2 tablespoons salted butter

12 large white button mushrooms, sliced

1 cup diced onion

1 pinch salt

2 tablespoons all-purpose flour

2 tablespoons ketchup

1 tablespoon Worcestershire sauce

3 cups high-quality, low-sodium beef broth

salt to taste

Melt 2 tablespoons butter in a large nonstick pan over high heat; add mushrooms, onions, and a pinch of salt. Saute, stirring occasionally, until very nicely browned, 5 to 8 minutes. Reduce heat to medium and add flour. Cook and stir for 3 minutes.

Stir in ketchup, Worcestershire sauce, and beef broth; increase heat to high. Bring to a simmer; reduce heat to medium and cook, stirring occasionally, until the gravy thickens slightly and reduces, about 10 minutes. Taste and adjust salt as needed. 

From Chef John's Salisbury Steak recipe.