Special equipment: an open fire set up with a grill grate; a sticky rice aluminum steamer pot and sticky rice bamboo steamer basket with lid
Rinse and drain the white sweet rice and black sweet rice in a sieve until the water is mostly clear and no longer cloudy, about 5 times. Transfer to a large bowl, cover the rice with water and soak for at least 4 hours and up to overnight.
Set up a hardwood fire and let it burn to low-burning embers (see Cook’s Note). Set up your grate for direct and indirect heat cooking.
Drain the rice, then place it in a sticky rice bamboo steamer basket. Fill a sticky rice aluminum steamer pot halfway with water and place on the grill grate over direct heat. Bring to a boil, then place the basket with the rice on top of the pot and cover with its lid. Cook until the rice is fluffy and cooked through, 15 minutes. Toss the rice until the bottom of the rice is on the top. Cook until the rice is tender and fluffy, 5 minutes more.
Make sure to use untreated hardwood, such as cherry, hickory or mesquite, that is safe for cooking.