Instructions:
- Rehydrate the Porcini: Place dried porcini mushrooms in a bowl and cover completely with 1 cup of boiling water. Let them soak for 15 minutes.
- Prepare Mushroom Liquor: Gently lift the soaked porcini out of the water (leaving any grit behind), roughly chop them, and strain the soaking liquid through a fine-mesh sieve into a separate cup. This strained liquid is your mushroom liquor.
- Sauté Fresh Mushrooms: Melt butter in a medium saucepan or deep skillet over medium-high heat. Add fresh mushrooms. Cook, stirring occasionally, until they are deeply browned and all their moisture has evaporated (about 8-10 minutes). Season lightly with salt and pepper.
- Build the Aromatics: Push the browned mushrooms to one side of the pan. Add the minced onion and garlic to the cleared space and cook until soft (about 3 minutes). Stir in the chopped rehydrated porcini and fresh thyme, cooking for 1 minute until fragrant.
- Make the Roux: Sprinkle the 3 tablespoons of flour over the entire mushroom mixture. Stir constantly for 2 minutes to cook out the raw flavour of the flour, creating a thick roux.
- Deglaze and Whisk: Slowly whisk in the reserved mushroom liquor first, scraping up any browned bits (fond) from the bottom of the pan. Then, gradually whisk in the remaining 3 cups of stock until the mixture is completely smooth.
- Simmer and Thicken: Bring the gravy to a gentle simmer over medium heat, whisking often. Reduce the heat to low and cook for 5 to 8 minutes until the gravy thickens enough to coat the back of a spoon.
- Finish Seasoning: Stir in the Worcestershire sauce. Taste the gravy and adjust salt and pepper as needed. If it is too thick, add a splash more stock; if too thin, simmer uncovered for a few more minutes. Serve piping hot.