How do you do THAT?

He would grind the grains, add this powder to a small pot, along with sugar, and pour in water equal to the volume of my mug, then boil it over high heat. But recently, he started doing it over low heat.

It's pretty much the same. The only difference is that I boil it over high heat, and when it boils, I turn the gas down to the lowest setting. After about half a minute, I add a little more heat, slightly above medium, and then turn it down again. I do this about three times.
I can't judge the taste, but it gives a good kick.