Preheat your oven to 225°F (110°C). Line a baking sheet with parchment paper. This will prevent sticking and create a clean, easy surface for baking.

In a clean mixing bowl, add the egg whites. Start whisking at a low speed, gradually increasing to medium as the egg whites begin to froth. Add the cream of tartar (if using) to ensure they whip up nicely.

Continue beating the egg whites until they form stiff peaks. They should hold their shape well when you lift the whisk out of the bowl. This is crucial for achieving the proper meringue texture.

Once you have stiff peaks, slowly add the superfine sugar one tablespoon at a time. Continue to beat the mixture on a medium speed until the meringue becomes glossy and the sugar dissolves completely. This can take around 5 to 7 minutes.

Gently fold in the vanilla extract, lemon zest (if using), and freeze-dried strawberry pieces. Be careful not to deflate the mixture; folding will keep your cookies light and airy.

Using a piping bag fitted with a star tip or a simple ziplock bag with a corner snipped off, pipe small mounds onto your prepared baking sheet. You can make them as big or small as you like, but consistency is essential for even baking.

Bake in your preheated oven for about 1.5 hours, or until the cookies are no longer sticky. They should lift off the parchment with ease. Once baked, turn off the oven and leave the cookies inside for an additional hour to allow them to cool and set properly.

After the baking process is complete, remove the cookies and let them come to room temperature. Once cooled, they are ready to be enjoyed!