Preheat the oven to 300° Fahrenheit
In a small bowl, sift together almond flour and powdered sugar. Set aside.
In a large bowl, whisk egg whites until foamy. Add cream of tartar and salt and whisk until combined.
Add granulated sugar, one spoon at a time, to the egg mixture while continuing to whisk. The mixture should reach soft peaks after all the sugar has been added.
Add lemon juice and yellow food color. Whisk until stiff peaks have been achieved.
Whisk in lemon zest.
Fold the almond mixture into the egg mixture (meringue). The batter should be runny enough that small peaks will dissolve into the batter.
Using a piping bag, pipe 36 oval shapes (more or less). Tap the baking sheet gently against the counter to get rid of any air bubbles in the battle.
Let rest for 30 – 45 minutes or until a skin has formed over the top of the cookies.
Bake for 15-18 minutes, one baking sheet at a time. Let cool completely.