Place the ground beef in a large bowl. Add the salt, pepper, dry mustard, and cayenne, and mix well with a fork. Add the ketchup, coconut aminos, apple cider vinegar, egg, and almond flour and gently mix with a fork until well combined. Cover the bowl with plastic wrap and refrigerate for 2 hours, or up to overnight if possible.

Meanwhile, in a large nonstick sauté pan over medium heat, heat 2 tablespoons clarified butter. Add the onions, mushrooms, and salt. Stirring continuously, sweat the mushrooms and cook until onions are transparent and juicy and mushrooms are brown, about 5 – 7 minutes. Stirring continuously, add the arrowroot, and stir to thoroughly coat the mushrooms. Then, add the ketchup and coconut aminos and stir to combine. Add the chicken stock and increase heat to medium high to bring to a low boil. Turn heat to medium, and simmer the sauce until it thickens, stirring occasionally about 10 minutes. Turn off the heat and set aside.

Divide meat mixture into four equal parts. Using your hands, form thick oval patties and place them on a baking sheet.

In a large nonstick sauté pan over medium heat, heat 2 tablespoons clarified butter. Gently add the patties to the pan and cook until brown, about 2 minutes. Gently flip to the other side and cook 2 more minutes—the patties may crack, but don’t let it scare you.

Carefully pour the gravy over the patties. If needed, reduce the heat so the sauce is gently bubbling, and cook the patties until done, about 5 – 6 minutes. Enjoy!