Preheat oven to 350 degrees. Combine the onion, green pepper, garlic and celery in food processor or blender. Process until finely chopped. Stir in some creole seasoning.
Cut slits across the roast about 1/2 inch deep. Pack the vegetable mixture into the slits. Coat the roast generously with the bacon gease. Rub the creole seasoning all over the outside of the roast.
Brown all sides of the roast on the top of the stove. Just enough on each side to slightly color it. Then place the roast in a roasting pan and cook uncover for an hour. Cover with foil and continue cooking for about 3 more hours.
After the roast is done, you can skim off some of the excess fat and thicken the drippings with a mixture of chicken broth and flour if you want to make a thickened gravy.
Serve with rice or potatoes and smother with the delicious gravy.