Using a fine mesh strainer and large bowl, sift together 150 grams of almond flour, 150 grams of confectioners' sugar, and 1/8 tsp salt. Toss any large chunks that will not strain.
Optional: Run the dry ingredients through a food processor for 15 seconds for an even finer batter. Do not overmix!
Add 75 grams of egg whites and 1/8 teaspoon cream of tartar into the bowl of a stand mixer. Use the whisk attachment and turn the mixer on medium to high speed and beat until soft peaks form. Set the mixer to low and continue on to make sugar syrup.
Add 60 grams water and 150 grams sugar to a small saucepan and bring to medium heat. Cook until the sugar dissolves completely.Then, stir regularly with a heat-proof spatula, and use the thermometer to check the temperature. Cook until the hot sugar syrup reaches 245 degrees, which will take around 5 minutes.
Make meringue: Quickly remove the pan from the heat, turn the mixer back to medium speed, and pour the hot syrup into the egg whites in a steady stream along the edge of the mixer bowl. Add 4-6 drops of gel food coloring. Increase speed to medium high and let the mixture whip for 3-4 minutes or until stiff peaks barely form. When done mixing he peak tip should bend off at 2 o clock so that it will look like a bird beak. See photos for reference!
Now, add the remaining egg white and the meringue to the almond mixture, gently folding together to start. Stir the batter by making a "J" motion with your spatula, hit the sides slightly as you go. Be a bit vigorous, this helps remove air pockets. Scrape down the sides as you go. The batter is done when it flows of the end of the spatula in a ribbon, and you can hold up the spatula and draw a figure 8 with the batter, without the batter breaking.
Insert the 1/2-inch tip into the pastry bag and fill up the bag with batter. Hold the pastry bag perpendicular to the sheet; we have found that going straight up and down is best. Fill in each pre-lined circle. Let the filling flow gently, then flick the tip upward to stop the flow of batter.
Rap the tray against the counter top 5-6 times to release air bubbles.
Let the macarons air dry until they are smooth to the touch, about 15-30 minutes. You should be able to touch them without leaving a mark.Preheat oven to 325 degrees. Place macarons into the hot oven, one sheet at a time, and bake for 12-13 minutes. See notes above on how to test for doneness.
Let the macarons cool on the tray for 15 minutes, then transfer to a wire rack. If the shells don't peel up easily, stick the whole tray in the freezer for 10 minutes.
When shells are cool, add 1-2 tsp filling to one side of the shell. Gently press on the top shell and squeeze the filling to the edges.
For best flavor, refrigerate for 24 hours before consuming (though I don't blame you for diving in earlier!).