Corn flour (about 1 handful for each roti you want to make)
Boiling water
Butter (for hands and to butter roti after cooking)

Put corn flour in a big bowl.  Add boiling water a little at at ime and stir into flour - just enough to dampen thoroughly.  Let cool til you can handle and knead til smooth.  Add a little more water if needed.
(Note: At this stage, you have the option of freezing the dough sealed in a ziploc bag for later use). 

Pull off handfuls of dough and roll together.  Butter hands work the dough into a flat circle between your palms.  Or, use a little flour on a flat plate and flatten with a moistened hand.  Take your time, as these are a little tricky to make.

Put roti on a hot griddle or dawa.  Flip when it no longer sticks to the griddle and is getting a little brown on the bottom.  Brown a little on both sides.  Best if you can then put on a small round grill rack over a hot burner to finish - puff both sides.  Remove and butter one side to keep soft.  Stack roti on tinfoil and wrap to keep warm before serving.