Gently combine the minced onions, butter, garlic, Worcestershire sauce, mustard, and the meat. Don’t overwork the meat or it will make the steaks tough.
Form into evenly sides oval steaks. Refrigerate for 15 minutes. Remove from fridge and season each side with salt and pepper.
Heat olive oil in a large skillet over medium-high heat. (Cast iron will sear the meat the best.)
Add the hamburger steaks and sear on each side for 2-3 minutes. Set aside.
Make the Gravy
Decrease heat to medium-low. Melt 2 Tablespoons butter to the pan and add the onions. Cook for 15-20 minutes, until the onions soften and begin to caramelize.
Add the chicken broth, beef broth, onion powder, garlic powder, and Worcestershire sauce. Run a silicone spatula along the bottom of the pan to lift up any remnants of meat, this will give the gravy extra flavor.
Mix in the cornstarch and cold water until combined.
Bring the gravy to a boil and whisk in the cornstarch mixture.
Continue to whisk and decrease heat to medium.
Finish the Meal
Add the steaks back to the pan and cover for 10 minutes, until cooked through. The internal temperature should be 160 degrees.
Swirl in the remaining 1 TBS cold butter at the end. This is a chef-inspired finishing technique that adds a velvety finish to the gravy.
Spoon the gravy on top. Sprinkle with parsley. Serve with mashed potatoes and rosted carrots!
