Combine all the steak ingredients in a bowl and mix to combine. Form into 6 large patties and place on a baking sheet pan.
Bake for 20 minutes.
Make the Gravy
Place the avocado oil and butter in a medium sized skillet and heat over medium heat.
Add the sliced onions and cook until soft and slightly browned.
Pour in the Worcestershire sauce and bone broth and bring to a simmer. Add salt and pepper then taste and adjust if needed.
Sprinkle in Glucomannan powder and continue to simmer on low heat and stir until gravy thickens, about 5 minutes. If it's not thick enough for your liking, simply sprinkle in another 1/4 teaspoon and allow to simmer on low until it thickens.