Step 1

Mix ground beef, egg, bread crumbs, Worcestershire sauce, Lipton onion soup mix, Dijon mustard, salt, and black pepper in a large bowl until well combined.

Step 2

Divide beef mixture into 4 equal portions and shape each into a burger patty.

Step 3

Preheat a large skillet over medium-high heat. Add the patties to the skillet and cook for 3-4 minutes on each side until golden brown. After cooking, move the patties to the slow cooker.

Step 4

Using the same skillet, add sliced mushrooms and minced garlic. Cook for 3-4 minutes, or until the mushrooms have softened, then transfer them to the slow cooker with the patties.

Step 5

In a separate medium bowl, combine cream of mushroom soup, beef broth, gravy mix, and Italian seasoning. Whisk until smooth. To adjust the thickness of the gravy, add more or less beef broth as desired. For a thicker gravy, mix in 1-2 tablespoons of cornstarch or 2-3 tablespoons of flour dissolved in cold water and then add to the gravy.

Step 6

Pour the gravy mixture over the patties and mushrooms in the slow cooker.

Step 7

Cover the slow cooker and set it to cook on low for 4-6 hours, or until the patties are fully cooked and reach an internal temperature of 160° Fahrenheit.

Step 8

Serve the Salisbury steak with gravy and your choice of sides, such as mashed potatoes, green beans, cauliflower rice, egg noodles, or your favorite.