In a large bowl, gently mix the ground beef with salt, pepper, and any desired seasonings until just combined. Divide the mixture into equal portions and shape them into oval patties about ½ inch thick.

Heat a large skillet over medium-high heat and add a combination of butter and oil. Sear the patties for 4-5 minutes on each side until browned.

Remove the patties and add sliced shallots to the skillet, cooking until golden. Then add sliced mushrooms and cook for an additional 5 minutes.

Stir in the mustard powder, then gradually add the beef broth, bringing it to a simmer. Let the gravy thicken for about 3-5 minutes.

Return the seared patties to the skillet, coating them in gravy, and let them simmer for 5-7 minutes on low heat.

Serve hot, garnished with freshly chopped parsley.