The open oven (Chinese: 挂炉) was developed in the imperial kitchens during the Qing Dynasty, and adopted by the Quanjude restaurant chain. It is designed to roast up to 20 ducks at the same time with an open fire fueled by hardwood from peach or pear trees. The ducks are hung on hooks above the fire and roasted at a temperature of 270 °C (525 °F) for 30–40 minutes. While the ducks are roasting, the chef may use a pole to dangle each duck closer to the fire for 30-second intervals. In open-oven style, the fat is usually melted during the cooking process, so the skin is crispy, and can be eaten separately as a snack.Almost every part of a duck can be prepared afterwards. Quanjude Restaurant served their customers the "All Duck Banquet" in which they cooked the bones of ducks with vegetables.