First, clean the yam with gloves, wash it, slice it and soak it in water. Without water, it is easy to oxidize and turn black. Like pears (peeling yam without gloves is itchy). After the water is boiled, put the yam into the pot. Turn off the heat and cook for 20-30 minutes. The thinner you cut it, the easier it is to cook. Cook until it tastes soft and waxy. Add rock sugar before cooking, and the dosage should be according to your own taste. Smooth, sweet and delicious!