In a large bowl combine all the steak ingredients : beef, breadcrumbs and egg. Shape into 4 oval patties.
Heat oil in a large pan on medium-high heat. Broil both sides of patties for about 1 minute . Then, take out from the pan.
The same pan and the beef juices can be kept on medium heat. Allow the onions to brown and add the mushrooms.
Add butter and garlic to the mushrooms. Cook for about one minute.
Stir in flour. Continue cooking, stirring until no lumps remain. Whisk in approximately 1/2 cup to 1 Cup beef stock. Mix until well blended.
Turn the heat up to High. Slowly pour the broth into a bowl and mix until it is well combined. Salt and pepper to taste .
Once the gravy is boiling, turn down the heat to medium. Slowly simmer, stirring occasionally, until gravy thickens. This should take approximately 5-10 mins. The gravy should be stirred around with the steak patties. Check the seasoning. If needed, add salt and pepper to taste.
Serve the steaks with mushroom sauce. They're great over pasta, rice, and mashed potatoes.