Preparation / Directions:
In a small bowl, combine the stuffing ingredients, mixing well. In a separate bowl, mix together the seasoned mustard ingredients. Make 12 to 14 deep slits in the steak with a knife, to form pockets, being careful not to cut through to the bottom. Stuff the pockets fully with the stuffing mixture, using it all.
Rub the surface of the steak thoroughly with the seasoned mustard. Cover well and refrigerate overnight. Keep refrigerated until ready to cook. Place the steak, stuffing side up, and the juices it has given off, in a heavy ovenproof 8-quart pan or large Dutch oven with as broad a bottom as possible, so the steak will lie flat. Sprinkle the onion and bell peppers on top of the meat and pour 1-1/2 cups of the stock around the edges and a little over the meat.
Cover pan and bake at 300F for 1 hour. Remove lid, push any pieces of onion and bell peppers on the sides of the pan back into the liquid, and continue baking uncovered just until tender and juices run clear, about 1 hour and 45 minutes more. The cooking time will vary according to the thickness of the steak. Remove the pan from oven and transfer steak to a platter. Skim off and discard fat from the pan juices. Spoon out about 3 tablespoons of the pan juices into a small bowl and mix with the flour until smooth.
Place pan over high heat and gradually stir in the flour mixture until well blended. Bring to a boil, then reduce heat and simmer until juices thicken up a little and flour is cooked, about 10 minutes more, stirring and scraping pan bottom frequently. Remove from heat and serve immediately with some of the pan gravy spooned over the meat and rice.
From the Prudhomme Family Cookbook -