Dissolve the brown sugar in the water (warm slightly if needed), then cool.
Sift the rice flour and tapioca starch into a bowl, and gradually mix in the sugar water, smooth.
Stir in the annatto powder and the lye water; the mixture will darken slightly. Strain.
Oil small silicone or metal moulds, and fill three-quarters full with the mixture.
Place the moulds in a steamer (wrap the lid in a kitchen towel so water doesn't drip in), and steam for 20-25 minutes, until the tops are set and springy.
Cool, unmould, and serve sprinkled with grated coconut.
A Receptnaptár original recipe. Calories and protein are estimated.
Tips
Lye water gives the characteristic chewy texture; use only the small amount stated.