Chef John's Best Mushroom Gravy

Ingredients

• 0.25 cups butter
• 1 package sliced mushrooms , 16 ounce
• salt to taste
• 0.25 cups all-purpose flour , or as needed
• 1 quart beef stock
• 1 pinch ground black pepper to taste
• 1 pinch fresh thyme leaves , to taste

Instructions

1. 1

   Heat butter in a saucepan over medium heat until it foams. Stir in mushrooms and season with salt. Simmer until liquid evaporates, about 20 minutes.

2. 2

   Stir in flour; cook and stir for 5 minutes. Add 1 cup of beef stock, stirring briskly until incorporated, then pour in the remaining stock and mix thoroughly. Season with black pepper and thyme. Reduce heat to medium-low and simmer until thickened, stirring often, about 30 minutes.