The Chinese words 豆 (dòu) and 豆子 (dòuzi) can refer to beans or peas. Therefore, you’ll need to add another character to the word to clarify what you are talking about.
豌豆 (wāndòu) are peas.
绿豆 (lǜdòu) are mung beans.
红小豆 (hóngxiǎodòu) are the little red beans used for making sweet red bean paste. They are often referred to simply as 红豆 (hóngdòu), although this term can be applied to any bean that has a reddish color. In fact, the Chinese call the red seeds of the Abrus precatorius (crab’s eye) 红豆 (hóngdòu) or 相思豆 (xiāngsī dòu love bean). 相思 (xiāngsī) is the longing between lovers or close friends. This word can be used as a noun or a verb. Before I looked up information about these seeds at this link, I did not know that they are poisonous. Young people give these to friends as a token of their affection, and I did receive a few of these seeds on a couple occasions before.
There is a well-known poem written by the famous poet 王维 (Wáng Wéi)
during the Tang Dynasty, or 唐朝 (Tángcháo).
Hóngdòu shēn nánguó,
Red beans grow in the country to the south,
chūn lái fā jǐ zhī.
and in spring they issue a few new shoots.
Yyuàn jūn duō cǎixié,
I hope you will pick a bunch of them
cǐ wù zuì xiāngsī.
as this thing evokes the most intense longing for a dear friend afar.
Soybeans are called 大豆 (dàdòu) or 黄豆 (huángdòu). As they say, “If you plant melon seeds, you will get melons; if you plant beans, then you will get beans.”
You will reap what you sow.
That is true if the conditions are favorable and the seeds germinate and grow, and the seedlings are not devoured by critters. Young bean shoots and the tender new growth at the tip of the vines are called 豆苗 (dòumiáo). They are delicious stir-fried or added to soups.
When the 豆荚 (dòujiá bean pods or pea pods) have swollen but still green, the seeds that you find in them are young and tender. At this stage, they are referred to as 毛豆 (máodòu fuzzy soybean) because of the fuzz covering the pods. In Japanese they are called edamame. The tender green seeds look somewhat like lima beans but have a smoother texture and a more subtle taste. They are excellent as a snack or in stir-fried dishes.
When fully ripened, the seeds are hard and take on a light yellowish color. Those are the 黄豆 (huángdòu soybeans) used for making soy milk, bean curds, bean pastes and sou nuts.
豆腐 (dòufu bean curd, tofu) is an important source of protein for many Asian vegetarians. Many Chinese drink 豆浆 (dòujiāng soybean milk) as part of their breakfast. 豆腐皮 (dòufupí) is the protein-rich film that floats to the top when you cook soy milk. This term also refers to very thin sheets of bean curd or the outer layer of deep-fried bean curd.
Tofu products are often flavored with 酱油 (jiàngyóu soy sauce), yet another food product made from the amazing soy beans.
Sweet bean pastes are called 豆沙 (dòushā). These are used as fillings for moon cakes, sweet rice dumplings, buns and many other snacks.
If you have a handful of soy beans, you could put them in a jar of water and grow your own bean sprouts, or 豆芽儿 (dòuyár). The soy bean sprouts are larger than the mung bean sprouts that are sold in the supermarkets.
Following are a few words that make use of the “bean” radical.
短 (duǎn) means short, brief, lacking or a weak point.
鼓 (gǔ) is a percussion instrument like a rattle or a drum. As a verb, this word means to strike (a musical instrument), to agitate or to swell.
厨房 (chúfáng) is the kitchen.
逗留 (dòuliú) is to stay or stop at a place.
登 (dēng) is to ascend or scale a height, as in 登山 (dēngshān mountain-climbing). To put an article in a magazine or newspaper is called 刊登 (kāndēng).
You already know how to draw a horizontal stroke to write the numeral 1 in Chinese. There is a set of more complicated characters used for writing the numerals on checks, banknotes and currencies to help prevent alterations. For the numeral 1, the “official” character is 壹 (yī). I’ll let you do some research and find out what the characters are that represent the other nine numerals.