Cream the shortening using a stand mixer with a cake paddle.
Add the confectioner's sugar one spoon at a time until all the sugar dissolves and the shortening becomes a lighter color.
Incorporate the salt and keep mixing. Then add the vanilla extract until it gets integrated.
Change the cake paddle and replace it with a hook. And add the sifted flour in stages. Mix for 1-2 minutes at medium speed.
The texture of the dough must be soft but malleable enough o to a ball and should not stick to the fingers.
Dust the working table with flour and remove the cookie dough from the mixer. Roll it and form a log.
Divide the log into three equal portions. One is for the white color, another for the cocoa brown color, and the third is for the pink color.
Cut the white dough portion into two equal parts and form two thin logs. Wrap them in parchment paper and refrigerate them.
Mix the pink edible gel color with one of the dough portions to create the pink color. You can integrate with your hands or use the mixer for an even color.
Take the last portion of dough and mix with the cocoa powder plus 1 teaspoon of shortening. Use your hands or the mixer. Adding that extra portion of fat helps to hydrate the dough and evenly mix with the cocoa powder.
Repeat the same process with the cocoa dough by dividing and creating two more logs.
Use egg whites as the glue that will form the tricolor log. Brush some egg white on one side of the pink log and press the pink and cocoa logs together.
Brush more egg white on top of the cocoa and pink logs and place the white vanilla log on top.
Wrap the tricolor log in parchment paper, roll it and place it on a baking sheet. Then cover with plastic wrap and refrigerate for at least two hours before baking.
Preheat the oven to 350F and cover a baking sheet with parchment paper.
Remove the wrapping and cut thin slices. Place the cookie slices in the baking sheet giving proper spacing between each cookiee.
Bake for 20 minutes. Remove one cookie from the tray, and if the bottom is light brown, the cookies are ready.
If the edges of the cookie become dark brown, the cookies are overdone.
Allow the cookies to cool for 30-60 minutes. Dust them with confectioner's sugar and store them in cookie tins in an airtight container with a lid.
These Mexican shortbread cookies will stay fresh for about a week when properly stored.