In the Food Processor or Magic Bullet, add freeze-dried strawberries, pulse for a few seconds, and then sift using a fine mesh strainer.
You can also crush them in a plastic bag using a rolling pin, more detailed instructions can be found in my Blueberry Macarons post. The powder should be without any large chunks, discard them before weighing it. You may need to process a few more grams of dried strawberries to obtain the amount listed in the recipe. Very important to weigh the powder after sifting it, not before.
How to Make Strawberry Macaron Shells
In the mixing bowl, sift together almond flour, powdered sugar, and strawberry powder.
Add egg whites to a clean and dry mixing bowl of stand mixer.
Whisk on low speed. Start adding sugar in a few parts. Add food coloring.
Set a timer for 5 minutes and whip meringue. After that, change the speed in the mixer to medium and whip for 5 more minutes. Then change speed again to higher and whip for 5 minutes. The total time for making French meringue is 15 minutes, with increasing speed every 5 minutes. I am making meringue in a Classic Kitchen Aid mixer and speed in 4-6-8.
Add sifted dry ingredients to the French meringue and fold the batter using a spatula. Do not overfold! Check the batter every 5 folds. The batter is ready when it flows fast from the spatula.
Transfer the batter to the pipping bag with a round tip. Line two baking sheet pans with a baking macaron mat.
Pipe macaron shells on the prepared baking mats. Hold the piping bag straight and apply pressure when you start pipping, then stop when you reach the desired size of the macaron shell.
Lightly tap the baking tray to remove air bubbles.
Use a toothpick or baking needle to remove the bobbles from the piped macaron shells.
Let macaron shells rest (dry) on the countertop for about 15 minutes.
Preheat oven to 300oF (150oC). Bake macaron shells in a preheated oven for 14-16 minutes. Baking time and temperature may be different, depending on your oven.
Remove the baking tray from the oven and let the macaron shells cool to room temperature before removing them from the mat.
Pair macaron shells with similar sizes before filling them.
Video
Notes
Measure all ingredients using a digital kitchen scale.
Weigh strawberry powder after sifting it, not before.
I do not age egg whites. I use them at room temperature.
Invest in a stand mixer; this will make your baking easier and faster.