Spread roast open, and pound with a meat mallet to 1 1/2- to 2- inch thickness. Season roast on all sides with garlic, ginger, salt, and pepper. Spoon dressing onto roast, spreading to within 2 inches of edge. Roll up jellyroll fashion, enclosing the stuffing completely. Tie roast securely with string. Make several slits on outside of roast, and stuff with chicken fat.
Place roast in a well-greased, covered roasting pan. Combine celery, carrot, green pepper, tomato, onion, lemon juice, bay leaf, and water. Pour vegetable mixture around roast. Cover and bake at 300° for 2 hours or until meat thermometer registers 170° (well done).
Transfer roast to a serving platter; remove string. Discard bay leaf, and reserve pan drippings for gravy. Let roast stand 10 minutes. Cut into 1/4-inchthick slices, and serve with Brown Gravy.