Make the tapioca pearls

1. Soak the tapioca pearls in cold water for 10 minutes.
2. Cook the tapioca pearls in boiling water until transparent (usually takes 10-15 minutes). Note: Don't add the tapioca pearls until the water starts boiling. Mix frequently to avoid sticking.
3. After 10-15 minutes, if the tapioca pearls become more transparent but have a white circle inside, cover the lid, turn off the heat and let them sit for 5 minutes. After that, check if the pearls are more transparent. 
4. Once the pearls are fully transparent, rain and rinse the tapioca pearls under cold water and set aside.

Make the mango sauce

1. Cut the mangos into cubes (save some slices for topping later). Put the mango cubes into a blender, add coconut milk and sugar. Blend until smooth then set aside.
2. Combine the mango sauce and tapioca pearls in a big bowl. This mixture will be the mango sago.
3. In a jar or a glass, add the mango sago and the coconut milk for topping on top. Enjoy right away or chill in the fridge for 30 minutes.
4. Top with fresh mango pieces and coconut flakes.