Line 2 baking sheets with parchment paper or silicone macaron baking mats.
Bring all ingredients wo room temperature.
Combine powdered sugar and almond flour and pulse in a food processor for 30 seconds. Sift through a sieve in a bowl. You can do this a couple of times. Discard the larger almond meal pieces.
Place 2 egg whites in a large bowl and beat until foamy. Gradually add the sugar then increase to high speed. Beat for 2-3 min or until stiff peaks form.
Add powdered sugar/almond mixture and fold with spatula from the bottom of the bowl upward then press the flat side of your spatula through the middle. Once all the dry ingredients are incorporated, add gel food coloring.Use a toothpick to add a little to color the batter to the desired color. Repeat the folding until batter gets to "lava like consistency" (floats like lava, like the ice cream from McDonalds, you can write the figure 8 without the dough breaking).
Fill a pastry bag with the batter. You need Wilton 1A tip, or you can just cut off the tip of the bag.
Pipe 1-inch round macarons onto the baking sheets. Tap a few times on the counter, to release the air. Let them dry for at least 30 minutes at room temperature, until they are not sticky to the touch.
While cookies are resting, preheat oven to 325 F. Rack should be in the middle, or slightly lower than the middle, but not higher. I do not use convection oven.
Bake macarons for 12-13 minutes. If you feel like they are starting to brown, lower the temperature to 300-285 and bake for 1-3 minutes longer.
Let macarons cool for 10-15 min at room temperature. Remove from the trays and fill with lime curd.