Rinse the dried scarlet runner beans and drain. Place them in a pot and add enough water to cover the beans by 5cm. Let them soak overnight.

Bring the beans to a boil over medium-high heat and cook for 2–3 minutes. Drain the water. Repeat this process once more with fresh water.

Rinse the pot, return the beans, and add enough fresh water to cover them by 5cm. Bring to a boil over medium heat, then reduce to low heat. Cover and simmer for 40–50 minutes, ensuring the beans remain submerged. Turn off the heat and let them rest for 30 minutes.

Add half of the sugar and simmer on low heat for 20 minutes without boiling. Add the remaining sugar and simmer for another 20 minutes. Stir in a pinch of salt gently.