Rinse the rice well, in a sieve under cold water. Soak the rice for at least an hour, or as long as overnight, before draining and rinsing it again.
If you have a rice steamer:
Steam the rice for 20 minutes, or until tender.
No-steamer method:
Put the rice in a saucepan with 1 cup + 2 tablespoon of cold water. Put a lid on the saucepan, bring it to a simmer, then immediately turn the heat down to low. Let the rice cook for 10 minutes without removing the lid or stirring it whatsoever. After 10 minutes the water should have all disappeared (a glass lid is really handy here). Turn the heat off and allow the rice to sit, with the lid on, for a further 5-10 minutes.
While the rice is cooking:
Heat the coconut cream, palm sugar and salt in a saucepan over medium heat, stirring constantly. Once the sugar and salt have dissolved into the coconut cream, remove ½ cup of the coconut cream and pop it in the fridge to chill and use later as a dipping sauce.
Once the rice is cooked:
Pour the remaining hot coconut cream over the rice and stir it gently to evenly coat the grains. Set the rice aside for 10-15 minutes to absorb the coconut cream and cool down enough to handle.
To assemble the mango sticky rice summer rolls:
Cut the cheeks off a mango, peel them, then slice thinly. You'll have more than you need (cook's treat!).
Set up a production line with rice paper wrappers, sliced mango, fresh mint leaves, the rice, and a casserole dish or wide shallow bowl with hot water in it.
Working one sheet of rice paper at a time, dunk the rice paper into the water for just a few seconds, then lay it on your bench or another smooth work surface. Spoon a heaped tablespoon of sticky rice onto the rice paper, in a spring roll sized shape towards the front edge. Arrange a mint leaf and a mango slice about halfway up the rice paper. Fold up the bottom edge, fold in the sides, then roll it away from you.
Assemble the finished rolls on a serving platter as you go. The summer rolls are best served fresh at room temperature soon after they’ve been made, but can be covered and refrigerated to serve later that day. If you’re serving them later, sprinkle a little extra water over the finished summer rolls and store them in an airtight container to stop them from drying out.