Preheat oven to 325 degrees F. Rub leg of lamb all over with cut sides of garlic. In a small bowl, combine parsley, celery salt, pepper, and paprika. Sprinkle parsley mixture evenly over lamb; rub in with your fingers. Place the lamb, fat side up, on a rack in a shallow roasting pan. Insert an oven-going meat thermometer in the center, making sure bulb does not touch bone. Roast, uncovered, for 1-1/4 hours.

Meanwhile, in a small saucepan, melt butter over medium heat. Add carrot and onion; cook 3 to 4 minutes or until vegetables are tender. Stir in bread crumbs. Remove lamb from oven. Carefully pat crumb mixture over top of lamb. Continue roasting for 45 minutes to 1 hour or until desired doneness (140 degrees F for medium-rare or 155 degrees F for medium). Cover with foil; let stand for 10 minutes before slicing. (The temperature of the meat will rise about 5 degrees F during standing.) Serve with warm or cooled Plum Jam Sauce. If desired, garnish with fresh plum wedges. Makes 10 to 12 servings.

In a medium saucepan, whisk together 3/4 cup plum jam, 1/4 cup unsweetened pineapple juice, 1 tablespoon orange juice, 1 teaspoon all-purpose flour, 1/4 teaspoon dry mustard, and dash ground mace. Cook and stir until thickened and bubbly. Cook and stir for 2 minutes more.