In a medium saucepan, bring 4 cups of water to a rolling boil over high heat. Once boiling, add 1 cup of sago and reduce the heat to medium. Cook for about 15 minutes, stirring occasionally, until the pearls become translucent. Remove from heat and let sit covered for an additional 15 minutes.

Carefully strain the cooked sago using a fine mesh sieve and rinse under cold water to remove excess starch. Transfer the pearls to a bowl of cold water to cool completely.

While the sago is cooling, peel and dice 2 ripe mangos. Place the mango pieces into a blender along with 1 cup of evaporated milk. Blend until smooth.

In a large mixing bowl, combine the cooled sago, diced mango pieces, and optional ingredients if desired. Pour in the blended mango mixture and stir gently until well combined.

Transfer the Mango Sago mixture into serving cups or a large dish, cover with plastic wrap, and refrigerate for about 1 hour. You can add ice to cool it down quickly if needed.