In a large mixing bowl, combine ground beef, breadcrumbs, chopped onion, egg, Worcestershire sauce, garlic powder, salt, and pepper. Mix until just combined; do not overwork the meat.

Divide the mixture into 4 equal portions and shape them into patties about 3/4 inch thick for even cooking.

Heat a large skillet over medium heat and add a tablespoon of olive oil. Once hot, add the patties and cook each side for about 4-5 minutes until browned and cooked through. Remove the patties from the skillet and set aside.

In the same skillet, add another tablespoon of olive oil if necessary, then add the sliced onions. Sauté the onions for about 5-7 minutes until they become soft and translucent.

Pour in the beef broth and soy sauce, scraping up any brown bits from the skillet for added flavor. Bring to a simmer.

If you prefer a thicker gravy, mix the cornstarch with water in a small bowl and then stir it into the gravy. Let it simmer for a few minutes until it thickens. Taste and adjust seasoning with salt and pepper.

Gently place the cooked hamburger steaks back into the gravy, spooning the sauce over them. Let them simmer together for another 5 minutes to meld the flavors.

Serve the hamburger steaks hot, drizzled with the savory gravy. They pair beautifully with mashed potatoes, rice, or steamed vegetables.