For the patties:
2 lbs lean ground beef
1/2 medium onion, finely chopped
4 large cloves garlic, finely chopped
3 tbs fresh parsley, finely chopped
2 tbs Worcestershire sauce (check that it is gluten free)
1/2 tsp black pepper
1/2 tsp seasoning salt (check that it is gluten free)
For the gravy:
1 tbs olive oil
1 1/2 medium onions, sliced into half-moons
8 oz fresh mushrooms, sliced
1/4 c fresh parsley, chopped
3 large cloves garlic, finely chopped
4 c beef broth
1 tbs Worcestershire sauce (check that it is gluten free)
heavy pinch mustard powder
2 tbs corn starch mixed with water to form a slurry
salt and pepper to taste
Preheat oven to 350 F.
In a large bowl, combine all the patty ingredients.
Mix well to ensure that everything is evenly distributed.
Divide meat mixture into 8 even portions.
Form each portion into a flat oval shape.
In a large skillet over medium high heat, brown the patties on both sides.
Once the patties are well browned but not cooked through entirely remove to a large deep covered oven proof casserole dish which will hold them in a single layer.
In the same pan that you cooked the patties in; add the olive oil and onions.
Saute the onions until lightly browned and softened.
Add the mushrooms and brown them lightly.
Add the parsley and garlic.
Saute for 1 minute before adding the beef broth, Worcestershire sauce and mustard powder.
Bring to a boil then reduce heat to a simmer.
Simmer, covered for 5 minutes.
Taste and season with the salt and pepper as desired.
Bring back to a boil then stir in the corn starch slurry.
Cook just until thickened.
Pour the gravy over the browned patties in your prepared casserole.
Bake at 350 F for 45 minutes to 1 hour.
Serve over prepared rice or mashed potatoes if desired.