Combine ground beef, bread crumbs, and egg in a large bowl. Season with a pinch of sea salt and black pepper, mix well, and shape into 2 oval patties.
In a large skillet add the olive oil and heat over medium-high heat. Add the patties and brown from both sides.
Add the ketchup, Worcestershire sauce, water, and mustard powder to the skillet with the patties. Cover the skillet and cook the patties for 20 minutes, until cooked.
Once the Salisbury Steaks are cooked, transfer to plates and serve with mashed potatoes. Enjoy!