Line two large cookie sheets with parchment. Set aside.
In medium bowl, sift together almond flour and powdered sugar. Sift a second time and then set aside.
In a large mixing bowl with whisk attachment, beat the egg whites on medium speed until foamy. Add cream of tartar and continue to beat. Slowly add sugar one tablespoon at a time. Increase the speed to medium high and beat until stiff peaks are achieved. Add lemon zest, vanilla extract, lemon juice. Beat on medium speed for one more minute. Add a small amount of yellow gel color at a time until you achieve desired color. Mix to incorporate.
Sift the almond flour mixture over the whipped egg whites. Gently fold the mixture together. The batter will look very thick at first, but it will get thinner as you fold. Take care not to over mix it. To test the batter consistency, drop a small amount of the batter and count to ten. If the edges of the ribbon are dissolved within ten seconds, then the batter is ready.
Transfer the batter into a pastry bag. Cut the tip off of the bag and pipe about a 1 inch dollop of batter onto parchment lined sheet. Place dollops about 1 inch apart.
Tap your cookie sheet on the counter to get any air bubbles out of the batter. Then let the batter rest for 15-30 minutes. (You want to be able to lightly touch the batter without having any stick to you finger.)
Preheat oven to 300 Degrees F. while batter is resting.
Once set place cookie trays in the oven on the center rack. Bake for about 10-15 minutes.
Remove from oven and let cool for 5 minutes on cookie sheet then carefully slide an offset spatula under each one and remove to a cooling rack.
Once cooled place about 1-2 teaspoons on one macaron and place another on top to make a sandwich.