Make several slits in roast, and stuff with garlic slices. Sprinkle with salt and pepper. Brown roast on all sides in hot oil in a large ovenproof Dutch oven. Pour 1/3 cup water over roast. Cover and bake at 325° for 2 hours or until tender.
Remove roast to a serving platter; keep warm. Combine flour and 1/4 cup water; stir until smooth. Pour flour mixture into pan drippings; cook, stirring constantly, until thickened and bubbly. Serve gravy with roast.