蘸 (zhàn) is a verb meaning "to dip" something into a liquid or sauce. It is commonly used when describing how food is eaten with a dipping sauce. For example, dumplings are often dipped in vinegar or soy sauce before eating.
吃饺子的时候我喜欢蘸醋。
Chī jiǎozi de shíhòu wǒ xǐhuān zhàn cù.
I like to dip dumplings in vinegar when eating them.
把面包蘸一点牛奶,味道更好。
Bǎ miànbāo zhàn yìdiǎn niúnǎi, wèidào gèng hǎo.
Dip the bread in a little milk and it tastes even better.
他拿起春卷蘸了一下酱油。
Tā ná qǐ chūnjuǎn zhàn le yíxià jiàngyóu.
He picked up a spring roll and dipped it in soy sauce.