Whisk the egg whites until stiff.

把蛋清打成稠的。

《牛津词典》

Whisk the egg whites into stiff peaks.

把蛋清搅成硬尖状。

《牛津词典》

Whip the egg whites up into stiff peaks.

把蛋白打得起稠尖儿。

《牛津词典》

Let me rephrase it into garbled English that'll lead more naturally into what I want to do While the egg whites are not stiff, beat them.

让我用篡改的英语,重新说一遍，我要做的吧,当蛋清还不够浓稠的时候，搅拌它们。

麻省理工公开课 - 计算机科学及编程导论课程节选

And I'm sure you don't remember, but one of the things I had in my recipe, is beat egg whites until stiff. OK.

我相信你们不记得了，但是我说过我食谱中的一件事情是，搅拌蛋清直到变浓稠，好。

麻省理工公开课 - 计算机科学及编程导论课程节选

Chill in the fridge and once cool, continue with the egg whites.

FORBES: LIVING HIGH ON THE (EGG) NOG

When the syrup is at about 235 degrees F, begin beating the egg whites on medium speed with the whisk attachment or with a hand mixer.

NPR: Recipe: Devil's Food White-Out Cake

While the syrup is cooking, start beating the egg whites.

NPR: Recipe: Devil's Food White-Out Cake