In every Thai city and village, the people know and love khao tom mad. It's a vegetarian dish too, so according to our sources it may be impossible to find a Thai person that does not like eating it. Although it's a dessert recipe, this is very filling and could be served as a main course. The black beans are optional.
Soak the sticky rice in water overnight, then drain and set aside. If you want to include the black beans soak them overnight also and boil until soft, or just use canned.
Combine coconut milk, sugar and salt (use a bit less if you prefer) in a separate bowl and stir until ingredients are dissolved. Put this mixture to a large pot or wok, then add the rice. Over medium low heat, stir constantly until the rice becomes tender and all the coconut milk is absorbed (about 15 minutes). Leave to cool.
On a piece of foil, set a few black beans in the middle then cover them with the rice (see pictures below). Place a sliced banana on top of the rice then cover that with rice, to form a small "roll" with the banana hidden in the middle. Add a few more black beans to the top.
Wrap this up in foil (as shown) then place in a stacked steamer (or similar steamer). Steam for 45 minutes (with the lid on). Remove and enjoy.