Wheat Flour
Flour
Small wheat powder is wheat flour, or flour.
こむぎこ
This word uses the kun'yomi readings of all three kanji. The 小 and the 粉 both use kun'yomi that you haven't learned yet, but luckily they are both the same! Just think about how "small" things are like "children" (子), and "powder" is also small. So both 小 and 粉 are read こ.
お水の三倍の量の小麦粉を入れてください。
Add three times more flour than water.
これは小麦粉を練って作ったお菓子です。
This is a sweet that is made by kneading flour.
うわっ最悪。さっき買った高級小麦粉、電車に忘れちゃった。
Oh no. I left the expensive flour I just bought on the train.