Combine ground beef, horseradish, Worcestershire sauce, minced garlic, kosher salt, and black pepper in a large bowl. Form equally-sized patties from the meat (6-8)
Over medium heat, add patties to a skillet and cook until browned on each side, roughly 5-6 minutes per side. Remove patties once browned and reserve half of the drippings in the skillet.
To the drippings, add mushrooms and onion. Cook until just tender. Add flour and cook for 1-2 minutes, stirring constantly.
Add french onion soup and beef consommé. Stir. Add beef patties back to the pan and bring to a simmer. Simmer for 30 minutes, allowing the patties to be cooked through and the sauce to thicken.
Serve patties with sauce, mushrooms, and onions on top -- enjoy!
Notes
Allow the sauce to simmer fully with the patties, which will allow it to thicken.
Do not add additional salt to the sauce without tasting, as the soup and consommé both have a lot of sodium.