Preheat oven to 325 degrees. Mix dressing, syrup and mustard, set aside.
Place ham, fat-side up, in roasting pan. Diagonally score ham (see instructions below); cover with foil. Bake 1 hour.
Remove foil. Brush ham with 1/3 of the glaze. Bake, uncovered, 1 hour or until heated through (140º), brushing with remaining glaze every 20 min.
Meanwhile, toss parsnips and carrots with olive oil in large shallow pan. Add to oven with ham the last 45 min. of the ham baking time, turning vegetables every time ham is brushed with glaze.
Remove ham from oven; transfer to cutting board. Tent with foil; let stand 15 min. Meanwhile, increase oven temperature to 425 degrees. Continue to roast vegetables 15 min., turning every 5 min. Serve with ham.
How to Score a Ham: Using a sharp knife, make 1/4-inch-deep parallel cuts, about 1 inch apart, in top surface of ham. Make additional scores at right angles to form diamond shapes.
Cook's Note: After carving the ham, reserve the bone for making Split Pea Soup.