Cut deep slits randomly in roast. Rub salt pork slices with pepper, and insert slices into slits. Rub entire surface of roast with garlic, salt, and flour.
Brown roast on all sides in hot shortening in a large Dutch oven. Add sliced onion, bay leaf, and 1 cup water. Cover and simmer 2 1/2 hours or until meat is tender.
Transfer roast to a serving platter. Remove bay leaf from gravy and discard. (Gravy may be thickened with additional flour, if desired). Serve gravy with roast.