Red beans are a good source of protein and in Asia, bean are preferred to be sweetened instead of salty. The simplest yet most satisfying dessert after a meal would be the red bean soup. In the hot summer months, this is served ice cold and in the winter months, it’s served piping hot. However it’s served, it’s a wonderful way to end a meal. There are many variations of red bean soup. The Cantonese style red bean soup usually contains dried tangerine zest (陳皮) flavor and thickened with tapioca starch. The Japanese zenzai (ぜんざい) is a thick soup almost like a porridge which is served with chewy glutinous rice balls or rice cakes. Korean style patjuk (팥죽) sometimes is garnished with pine nuts and a dash of cinnamon. Taiwanese red bean soup is simpler, with just red beans, water, and sugar. If you move down towards southeast Asia, coconut milk is usually added into the soup as well as sago. Feel free to experiment with different add-ins once you have the base red bean soup prepared. For me, I prefer the Taiwanese style, light and soupy.
Now, the BIGGEST MISTAKE one can make when cooking the red bean soup is to add sugar in the beginning of cooking. If you add the sugar to the beans before they are tender, they will NOT soften, ever. It’s a strange phenomenon to witness and if I have time, I’d like to find out why that is the case and whether it only happens to red bean or the same would apply to green beans and other beans. Regardless, you have been warned. I’m pretty sure with modern equipment like a pressure cooker or an immersion blender, you can probably add sugar in the beginning and just blend the whole thing at the end. But this time, let’s keep to tradition and only add sugar at the end.
In terms of ingredients, the red bean is commonly referred to in America as Japanese adzuki (あずき) beans. The sugar can be white granulated or the clear rock sugar or palm sugar or even brown sugar. Whatever sugar you end up using, the flavor would be subtle but noticeable. Lastly, the pinch of salt is an ingredient to trick your brain to think the soup is sweeter than it is. Growing up in Taiwan, I’ve always had slightly salted fruits, especially pineapples and watermelons. The ‘adults’ say it makes the fruit taste sweeter. I just find it salty. But for the soup, since it is only a tiny pinch, it’s not going taste any salty at all. Maybe next time I should do a blind taste test to see if I can really tell the difference. Anyway, enough rambling, time to make some red bean soup. And the best part about making a lot of red bean soup? I freeze them to make red bean popsicles. 
Ingredients
- 16 oz dry adzuki red beans (about 2 cups)
- ½ cup sugar**
- Pinch of salt
- Water
** sweetness is a personal preference so you can make adjustments as you feel like it
- 16 oz dry adzuki red beans (about 2 cups)
- ½ cup sugar
- Pinch of salt
- Water
- Wash and soak beans in water for 8-10 hours or overnight
- Add beans to a pot of water so that the water is about 2-3” above the beans
- Bring to a boil for 5 minutes and skim off scum from the soup
- Simmer for 2-3 hours until beans are tender (you can adjust the time based on your preference)
- Add sugar and a pinch of salt
- Stir until sugar has dissolved and simmer for another 15-30 minutes
- Serve hot or cold
Can we use tinned red kidney beans for this recipe and shorten cooking time accordingly ?
Give it a try. I think it would work as long as the canned beans are just cooked in water and not broth. I recently used black beans to make the same recipe. ~Mike