Louisiana Roast Beef

1/4 cup finely chopped onions
1/4 cup finely chopped celery
1/4 cup finely chopped green bell pepper
2 tablespoons butter or margarine
1 teaspoon salt
1 teaspoon white pepper
3/4 teaspoon black pepper
3/4 teaspoon minced garlic
1/2 teaspoon dry mustard
1/2 teaspoon cayenne pepper
1 beef roast (3 1/2 to 4 pound boneless with layer of fat on top)

In a small bowl combine onion, celery, bell peppers, butter and seasoning. Mix well.

Place roast in a roasting pan, fat side up. With a large knife, make 6 to 12 deep slits in meat to make pockets. Do not cut all the way through. Fill pockets with vegetable mixture. Reserve 1 tablespoon to rub over top of roast. Bake at 300 degrees F until meat thermometer reads 160 degrees F for medium, about 3 hours.

Serve immediately, topped with pan drippings.