*If Szechwan peppercorns are difficult to find, then you can substitute cardamom seeds for the fragrant spices in this recipe. If you don't have a rotisserie, you can roast the ducks in the oven on a rack in a roasting pan. Roast the ducks at 500 degrees F for 30 minutes, then turn the heat down to 350 degrees F and continue roasting for another 50 minutes or more until the juices run clear and an instant read thermometer inserted in the thigh reads 175 degrees F. (It takes longer to cook the ducks on a rotisserie over a grill because you have to keep the fire low to avoid flare-ups from the dripping duck fat.)