Soak the rice in cold water for 2 hours. Drain. Line a steamer with cheesecloth, heat steamer & lay rice on the cheesecloth. Steam for 30 minutes or until cooked through. The rice will become glossy.
Mix the SEASONINGS ingredients in a large bowl & gently mix in the hot steamed rice. Cover tightly & let soak for 30 minutes to absorb the coconut flavour.
Blend the SAUCE ingredients in a pot & heat until it just reaches the boiling point. Let cool.
Peel the mangoes, slice lengthwise & remove the pits.
Divide the rice among 6 plates. Place mango slices on top & cover with the sauce. Sprinkle with the sesame seeds & serve.