When cooking white fungus soup, you generally don’t need to add sugar at the beginning. Although you can add sugar at the beginning, if you don't stir it all the time, it will easily stick to the pan. It is also not advisable to add sugar after cooking, because the rock sugar takes a while to melt and is not easy to taste. It is recommended to add sugar when it is almost cooked. Stir occasionally when adding sugar. Wait for the rock sugar to melt and then cook for 10 to 20 minutes to add more flavor.