Add ground beef, salt, pepper, 2 teaspoon worcestershire sauce, minced garlic, and ¼ of the onion finely diced to a large bowl. Mix gently with your hands until combined.
Form mixture into 8-10 patties. Place on a tray, cover, and transfer to the fridge while you make the gravy.
Add oil to a large skillet over medium low heat. Add sliced onions and saute for 5-7 minutes until softened and lightly caramelized.
Add butter and sliced mushrooms and continue to cook until mushrooms have browned and wilted, another 5-7 minutes.
Transfer cooked mushrooms and onions to a bowl and set aside.
Turn heat to medium high and add half of the patties. Brown patties on both sides. Transfer to a plate and brown the remaining patties. Set aside.
Return cooked onions and mushrooms to pan. Add beef broth, soy sauce, and the remaining worcestershire sauce. Bring to a simmer.
Whisk together corn starch and remaining beef broth. Add it to the pan and continue to cook until the gravy thickens, around 5 minutes.
Return all of the patties to the gravy and simmer on low until ready to serve.