Prepare all the ingredients, start the pot, pour in 1000 grams of cold water, boil over high heat, after the water is boiled, pour the sago, turn off the heat and simmer, cook until the sago only has small white hearts, then turn off the heat. Simmer for 20 minutes, the sago is simmered until completely transparent, remove, put the removed sago into a cool boil, rinse after cooling, put the rock sugar in the coconut milk, stir on low heat until the rock sugar melts, remove the sago, Control the moisture, pour the sago and coconut milk into a bowl and set aside. Peel the mango and cut into small pieces. Put the diced mango into the sago coconut milk, stir and refrigerate for 30 minutes. After refrigerating, serve. Ready to eat