Put dried beans in a pot with water (about 3-4 times the volume of the beans), and cook just to before boiling. Remove from heat, cover, and leave overnight.

Put the pot on the stove and start cooking. Cook at medium heat and let boil for a few minutes. Drain the water. Put the beans back in the pot, and add clean water to the pot (2 inches above the beans). Cook at low heat about one hour or so, covered. Check water level from time to time, and add more as needed so the beans are not above the water.

When the beans become very tender (check by pushing a bean with fingers), drain water but save 1 1/2 cups of liquid. Put beans back into the pot with the reserved liquid and 1/2 of the sugar. Stir to mix, cook for 3-4 minutes at medium heat, then turn off, and cool. Add the rest of the sugar, stir, and cook at medium heat for 3-4 minutes. Remove from heat, cover, and cool to room temperature.