1. In a pot, bring water to a boil. Once the water starts to boil, add chrysanthemum. Simmer for a minute or two (do not simmer for too long). Add rock sugar to taste and turn off the stove when the sugar has dissolved. Serve the drink at room temperature or chilled.
2. Take out the chrysanthemum flowers and seve the liquid through a strainer. Drink chilled or at room temperature.