小葱拌豆腐，一青二白

小葱拌豆腐，一青二白

Literally means:

a dish of white bean curd and green scallions

Actually means:

be as clear as daylight; a black-and-white situation

White bean curd decorated with a bit of green onion is characterized by the sharp contrast of white and green.

The characters 青 and 清 clear, are homonyms, so the phrase means one is innocent or stainless.

It may also mean that a thing is very clear.

雪白的豆腐上放一点绿色的小葱，颜色青白分明。这里利用同音关系，用“青”指“清”。

比喻某人清清白白，没有污点。也比喻事情十分清楚。