Pour the water and dry amaranth in a pot with a tight-fitting lid and heat on a medium heat. Bring to the boil.
When boiling, reduce the heat to low and cover. Simmer for 20 minutes.
After 20 minutes, the mixture should be thick but not glue-like. If it is too thick, add more liquid and mix through. If it is too watery, simmer uncovered for another 5-10 minutes.