Whisk together the ground beef, breadcrumbs, chopped onion, minced garlic, egg, Worcestershire sauce, Dijon mustard, dried thyme, salt, and pepper in a large mixing bowl. Thoroughly blend all ingredients.
Form each of the four equal pieces of the mixture into an oval-shaped patties that are about 3/4 inch thick.
In a big skillet, heat the olive oil over medium-high heat. Brown the Salisbury steaks in a pan over medium heat for four to five minutes each side, or until done. Lay the steaks aside after taking them out of the pan.
Melt the butter in a separate pan over medium heat. Toss the flour into the melted butter and stir until combined. Stirring continuously, heat for 1-2 minutes until the raw flour flavor is cooked off.
While scraping the pan for any browned pieces, slowly whisk in the Worcestershire sauce and beef broth. To thicken the gravy, bring the ingredients to a simmer and cook for two or three minutes.
To taste, add salt and pepper to the gravy. A little additional beef broth may be added to thin up the gravy if it becomes too thick.
Put the Salisbury steaks back in the pan and dollop some gravy on top. Allow the steaks to cook through and the flavors to combine by simmering for 2-3 minutes.
While still hot, ladle the remaining gravy over the Salisbury steaks and serve.
Serve with chopped parsley as a garnish, if desired.
For a hearty and filling dinner, try serving your homemade Salisbury Steaks over rice, noodles, mashed potatoes, or your favorite veggie side.
