Put red beans in a pot with 4-5 cups of water. Let boil for 5 minutes and discard water.

In a clean pot, place red beans and 4-5 cups of water, cover, and let simmer at low heat for 1 1/2 to 2 hours (add more water to keep above the beans). Or beans can be cooked in a pressure cooker if you want, which takes only about 20 minutes. The beans should now be very soft, easily crushed between fingers.

Mash up the cooked beans along with some of the cooked water in a food processor for 2 minutes. It will become a very loose paste. Strain through a fine mesh sieve (discarding the skin etc. in the sieve).

Put the strained paste in a pot with sugar, and cook at medium low heat stirring constantly about 15 minutes. It will become very thick and shiny. Transfer the paste to a flat container (such as a sheet pan) and cool.