Place some parchment paper on a large baking sheet and preheat the oven to 200°F.
Whisk the egg whites in a large bowl until it becomes foamy and opaque.
Pour the lemon juice and set the hand mixer to high. Whip until some hard peaks form.
Continue to beat while adding erythritol gradually one tablespoon at a time.
Add the lemon zest slowly.
Stuff the mixture into a piping bag. Squeeze the bag to form cookies on the baking sheet lined with parchment.
Place in the oven and bake. After 1 hour, turn the oven off but leave it close to cool the cookies completely. Leave it for about 1-2 hours before taking the sheet out. Transfer to a serving dish and enjoy!