1. With knife, remove skin and excess fat from pork leg, leaving only a thin fat covering. Place pork leg, fat side up, on rack in open roasting pan. Rub pork with 1 teaspoon salt. Insert meat thermometer into center of thickest part of pork, being careful that pointed end of thermometer does not touch bone. Roast in 325°F. oven about 4 hours or until meat thermometer reaches 170°F. (35 to 40 minutes per pound). Pork near bone will be slightly pink. If you prefer that no pink shows, roast until meat thermometer reaches 185°F. Remove pork leg from oven.
2. In small bowl, mix mustard, Worcestershire, and ginger. In 1-quart saucepan over medium heat, melt butter or margarine; remove saucepan from heat. Into saucepan, tear bread into small pieces. Add chopped parsley; mix well.
3. Skim 1 tablespoon fat from drippings in roasting pan; add to mustard mixture. With pastry brush, brush mustard mixture onto pork leg. With hands, carefully pat bread-crumb mixture onto pork. Return pork to oven; bake 15 minutes longer or until bread is browned. Place pork on large platter or cutting board. Let stand 15 minutes for easier carving.
4. Meanwhile, prepare gravy: Remove rack from roasting pan; pour drippings into 2-cup measure or medium-sized bowl (set pan aside); let stand a few seconds until fat separates from meat juices. Skim 3 tablespoons fat from drippings; pour into 2-quart saucepan; skim off and discard any remaining fat. Add 1/4 cup water to roasting pan; stir until brown bits are loosened; add to meat juice in cup with enough additional water to make 1 1/2 cups.
5. Into fat in saucepan over medium heat, stir flour and 1/4 teaspoon salt; gradually stir in meat-juice mixture and milk; cook, stirring, until gravy thickens slightly and boils. Pour gravy into gravy boat.