Save and Share how to make Sago in Mango Sago. It’s actually called tapioca pearls and the process in cooking them has a few steps. First you simmer on low heat for ten minutes and occasionally stir to avoid clumping. Next turn off the heat and cover with a lid for 15 minutes to finish cooking. Lastly rinse and strain to remove excess gel. To make the Mango Sago you need champagne mangoes, coconut jelly, sago, evaporated milk, coconut milk and condensed milk. Mix it all together and refrigerate