Preheat the oven to 325 degrees F. Place ham on rack in shallow roasting pan. Tent with foil; crimp foil to pan edges. Roast 1 to 1-3/4 hours, until internal temperature is 130 degrees F.
Remove foil from ham. In medium bowl stir together preserves and mustard; set aside 3/4 cup. Brush remaining on top and sides of ham. Sprinkle with peppercorns. Cover cut side of ham with foil to prevent drying. Roast 20 to 30 minutes or until internal temperature is 140 degrees F. Remove from oven; remove foil. Let stand at least 15 minutes.
Meanwhile, for sauce, in small saucepan combine reserved apricot mixture and snipped apricots, if using; heat through. Slice ham; serve warm or at room temperature with sauce. Garnish with apricots and lettuce. Makes 16 to 20 servings.