There is a kind of leaf, which you see in the photos, that can dye the rice grains into red or purple color though the leaves are totally green. It is called "purple leaf", and I was told that the color the leaves produce varies from trees to trees they grow in.
The leaves have no taste, no smell, they only produce color when you boil them with water. The less water and more leaves you use, the darker the color you will get. Use this water to soak the glutinous rice for 8-10 hours, you’ll get the rice dyed.
Outside Vietnam, I wonder if you can get these leaves. This dish was named according to the name of the leaf – "purple leaf sticky rice". Even if there is not, beetroot is a very good choice to dye other ingredients when you want create something more interesting to the normal foods.
I served this red sticky rice with grilled ground pork.