Soak the dried red kidney beans in a bowl with enough water to cover them for 6 hours to overnight. Drain the water.

Bring 600cc of water to a boil in a pot. Add the soaked beans and simmer over medium heat. Once boiling, reduce to low heat, skim off any foam, cover, and cook for about 1 hour until the beans are tender enough to crush with your fingers.

Add one-third of the sugar (50g) to the pot, stir until dissolved, and skim off any foam. Repeat this process with the remaining sugar in two batches.

Cover the pot again and simmer on low heat for 1 to 1.5 hours.