Add 1 cup of sweet rice to a rice cooker. Follow the water ratio specified on the rice or rice cooker instructions.
In a saucepan, combine coconut milk, sugar, and salt.
Heat over medium heat, stirring until the sugar is fully dissolved. Do not boil.
Once the rice is done cooking, pour half of the warm coconut mixture over the rice. Gently mix to coat and let it sit for about 10 minutes so the flavors absorb.
Make a cornstarch slurry by mixing 1 tbsp cornstarch with 2 tbsp water.
Add the slurry to the remaining coconut mixture in the saucepan. Heat while stirring until the sauce thickens slightly.
Slice fresh, ripe mangoes. Plate the sticky rice next to the mango slices. Drizzle a generous spoonful of the thickened coconut sauce over the rice.
Serve immediately, and enjoy this creamy, sweet, and fruity dessert!