In the same skillet, melt the butter over medium heat. Add the chopped onion and cook, stirring occasionally, for about 3-4 minutes until softened.
Add the sliced mushrooms and cook for 5-7 minutes, stirring occasionally, until the mushrooms are browned and tender.
Add the minced garlic and cook for an additional 1 minute, until fragrant.
Sprinkle the flour over the mushroom mixture and stir to coat the vegetables. Cook for 1-2 minutes to eliminate the raw flour taste.
Slowly add the beef broth while stirring constantly, making sure the flour mixture dissolves and the sauce thickens.
Stir in the Worcestershire sauce, soy sauce (if using), thyme, and salt and pepper to taste. Bring the gravy to a simmer and let it cook for 3-5 minutes, until it has thickened to your desired consistency.
3. Combine and Serve:

Return the cooked Salisbury steaks to the skillet, spooning the mushroom gravy over the top of each patty. Let the steaks simmer in the gravy for 5-10 minutes, allowing the flavors to meld together.
Taste the gravy and adjust the seasoning with more salt and pepper, if necessary.
4. Serve:

Serve the Salisbury steaks with the mushroom gravy over mashed potatoes, rice, or egg noodles. You can garnish with fresh parsley for a pop of color, if desired.
Tips:

Make-Ahead: The Salisbury steaks and gravy can be made ahead of time. Just reheat in a covered skillet over low heat, adding a little more broth or water if the gravy thickens too much during storage.
Mushroom Variety: Feel free to experiment with different types of mushrooms, such as cremini, shiitake, or even portobello, for a more earthy flavor.
Sides: This dish pairs wonderfully with mashed potatoes, roasted vegetables, or a side of sautéed greens.
This Salisbury Steak with Mushroom Gravy recipe is a hearty, comforting meal that’s sure to please everyone at the table. The savory, flavorful beef patties paired with the rich, creamy mushroom gravy make for a satisfying dinner! Enjoy!