Use a mixer to whip the egg whites, add a few drops of lemond juice or white vinegar, then add the 50g sugar in 3 additions, whip until stiff peaks form.

• 蛋清用打蛋器打成粗泡，可以加一点点白醋或柠檬汁，并且将50克白糖分三次加入，打发成硬性发泡。