After rinsing the rice three times, pour into a deep stockpot and cover with twice the amount of water. Add 1 tablespoon of salt to the water. Bring to a medium boil until rice is cooked, about 20-25 minutes. Drain the rice and set aside.
NOTE: Black Thai rice is a nutty and chewy rice even when cooked. Therefore, you should feel a bite back when chewing, but the rice will be cooked through.
Pound the ginger, coriander root, salt and garlic into a paste. Season with sugar, vinegar, curry paste and soy sauces. Then, add chili and coriander leaves. Set aside.
In a heavy skillet pan, add a bit of peanut oil, then add the fresh mango, coconut cream, and mango juice. Bring these elements to a low boil until evenly emulsified. Stir in the curry paste. Finely add the rice and stew for about 6-7 minutes until rice has absorbed most of the liquid. Add scallions and crab meat and serve.