Preheat the oven to 300°F (150°C). Line 2 baking sheets with parchment paper, or teflon sheet, or silicone mat.
To prepare the dry ingredients. Place the freeze-dried strawberries between two sheets of parchment paper. Using a rolling pin, crush the strawberries into a fine powder. (TIP: Do this step right before you begin making macarons because the strawberry powder draws in moisture and affects the texture of the batter.)
Sift together, prepared strawberry powder, almond flour and powdered sugar twice. (Note: If you have up to 2 tablespoons of chunky dry ingredients left in the sifter, you don't have to replace it. Simply discard those chunky bits.)
To make meringue, in a clean mixing bowl with a whisk attachment, combine egg whites, granulated sugar, cream of tartar and salt and beat the mixture on medium speed until soft peaks form. (I set it to speed 4 on my KitchenAid stand mixer. It takes 30-40 minutes to whip the meringue, but it's well worth it for nice and full shells.)
When the meringue reaches soft peaks, add pink gel food coloring.
Continue beating the meringue at the same medium speed until hard peaks form. Visual cues: Meringue should ball up inside the whisk, and when you lift the whisk, the meringue should hold a pointy end and have sharp ribs.
To make batter, sift almond flour mixture into the meringue. Using a silicone spatula, fold the dry ingredients into the meringue until fully incorporated. Then continue to fold the batter until it’s runny enough to draw a figure eight. To test, take a small amount of batter and drop it into the bowl. If the small peaks dissolve into the batter on its own in about 10 seconds, the batter is ready. If not, fold couple more times and test again. Be careful not to over-fold the batter. (TIP: Making french macarons is all about the technique. This is one of the most crucial step. Let me try to describe the folding motion as best as I can: run the spatula clockwise from the bottom, up around the sides and cut the batter in half. If you’re beginner macaron-baker, I suggest to count every fold. It takes roughly about 50 folds to reach the proper consistency. After 50 folds, start testing the batter, and continue testing after every couple folds.)
To pipe macaron shells, transfer the batter into a pastry bag, fitted with a round tip. (I use this Wilton 2A tip.) To pipe heart-shaped macarons: Place the template with hearts under the parchment paper on a baking sheet. Hold the pastry bag at straight 90° angle and pipe the batter as if you’re drawing two hooks facing each other, tracing the template. Download my free macaron template. Tap the baking sheets firmly on the counter (or slap the bottom of the baking sheet with one of your hands) a few times to get rid of any air bubbles. You can also use a toothpick to burst some large air bubbles. This step ensures smooth tops.
Let the macarons rest on the counter for 15 minutes before baking.
To bake, bake the macarons for 15-18 minutes, one baking sheet at a time, on the middle rack. It’ll take longer for larger macarons. To test for doneness, touch a macaron lightly and try to move it. If it slides and wobbles, bake a minute or so longer. The cooked macarons should be firm to touch and the base shouldn’t move.
Cool the macarons complete and then remove the shells from the baking surface. (TIP: Don't remove the shells while warm, you may risk breaking the shells, or the bottom might get stuck to the baking surface.)