2Add half a cup of panko bread crumbs to the grated onion and mix with your fingers for about 5 minutes, allowing the bread crumbs to soak in the onion juices.
3Add one pound of ground beef, one whole egg, three tablespoons of Dijon mustard, two tablespoons of ketchup, half a teaspoon of Worcestershire sauce, one or two minced garlic cloves, and one beef bouillon cube (broken up) to the mixture.
4Use hand mixers to combine all the ingredients until beautifully mixed.
5Form the mixture into five patties.
6Place the patties on a hot oiled pan and sear them on both sides.
7Remove the seared patties and set them aside on a plate.
8In the same pan, sauté the other half of the onion, diced, and two more minced garlic cloves until beautiful.
9Add two cups of sliced mushrooms to the pan and sauté until done.
10Add two tablespoons of butter and three tablespoons of flour to the pan with the sautéed onions and mushrooms, mix, and cook to create a roux.
11Slowly pour in two cups of beef broth, mixing constantly until all lumps are gone and deglaze the pan.
12Add two teaspoons of Worcestershire, a little bit of salt, and a little bit of pepper to the gravy and stir.
13Bring the gravy to a simmer.
14Return the patties to the simmering gravy and let them simmer until the sauce thickens and the patties are cooked through.
15Serve the Salisbury steak with mushrooms and gravy over mashed potatoes.