Hong Dou Tang (紅豆湯)

Hong Dou Tang is the most gentle and universally loved of all Cantonese tong sui — sweet soups — sipped warm after dinner or at late-night supper stalls throughout Guangdong and Hong Kong. Red adzuki beans are simmered for hours with dried tangerine peel and rock sugar until they split and dissolve into a thick, ruby-red soup of comforting sweetness. It is said to nourish the blood and calm the mind.

Serves: 4

Ingredients

• 300g (10½ oz / 1½ cups) dried adzuki (red) beans, soaked overnight
• 1.5 litres (6 cups) water
• 1 small piece dried tangerine peel (chen pi), rinsed
• 80–100g (3–3½ oz) rock sugar (bing tang), to taste
• Optional: 2 dried longan (gui yuan) or 30g (1 oz) lotus seeds, soaked

Instructions

1. Drain soaked beans and rinse. Bring to a boil in a large pot with 1.5 litres fresh water and the dried tangerine peel.
2. Boil vigorously for 10 minutes, skimming any foam. Reduce heat to the lowest simmer.
3. Cover and cook for 1 hour 30 minutes to 2 hours, until at least half the beans have burst open and the broth is thick and deeply red. Stir occasionally.
4. Alternatively, use a slow cooker on LOW for 8 hours.
5. Add rock sugar in the last 15 minutes of cooking. Stir until fully dissolved and taste — the soup should be pleasantly sweet but not cloying.
6. Add dried longan or lotus seeds (if using) with the rock sugar and allow them to soften.
7. Serve warm in bowls. Leftovers thicken considerably — thin with a splash of hot water when reheating.

Cook's Notes: Do not add sugar until the beans are fully cooked — sugar hardens bean skins and will prevent them from softening if added early. Chen pi (aged dried tangerine peel) is available at Chinese herbalists; even a tiny piece gives the soup a distinctive fragrant lift. The soup can also be served chilled in summer.