Rinse the glutinous rice 4-5 times until the water runs clear. Soak the rice for 4-5 hours. After soaking, drain the rice well. Bring water to a boil in a steamer, then place the rice in cheesecloth and steam for 25 minutes. Once done, transfer the rice to a bowl.

Pour the coconut milk into a pot. Add salt, sugar, and the pandan leaf (tied into a knot). Heat over medium, stirring until the sugar and salt dissolve. Taste to make sure the flavor is sweet and slightly salty. Simmer until the coconut milk is bubbling, then remove from heat.

Slowly pour half of the hot coconut milk over the freshly steamed rice. Stir to combine, but don't add all the coconut milk at once to avoid making the rice too wet. Cover and let sit for 10 minutes. After 10 minutes, uncover and stir the rice again, then cover and let sit for another 10 minutes. Serve the sweet coconut sticky rice with ripe mango.