Walnut Egg-White Cookies (Orehovki)

1. First step is whipping the egg whites. The bowl and the mixer beaters must be completely dry so the mixture whips up stiff. It's best if the egg whites aren't fresh — leaving them about a day makes them more homogeneous and easier to whip, though fresh ones are fine too. Whip the egg whites with a pinch of salt, ideally with a mixer. Gradually add the powdered sugar, vanilla and lemon juice a little at a time and whip to stiff peaks.
2. Then gradually add the finely ground walnuts and fold very carefully — not with a mixer but with a spatula or wooden spoon — so the egg whites stay as stiff peaks. Once the walnuts are evenly distributed, use a spoon to scoop the mixture and shape orehovki of the desired size onto a tray lined with baking paper. Keep in mind that during baking the orehovki relax and spread, so leave plenty of space between them so they don't stick together. Bake in an oven preheated to 150°C until they turn lightly brown, about 25 minutes.

Preparation time: 15 minutes prep, 25 minutes baking.