These cupcakes are inspired by EPCOT's Mexico Pavilion!
Zest the limes and mix with the sugar. Let this sit to infuse for one hour. In the meantime, line 2 cupcake pans with 24 liners and preheat the oven to 350 degrees.
After the sugar has sat for one hour, combine all ingredients but the egg whites in a stand mixer or large mixing bowl. Beat for 2 minutes on high.
Add the egg whites and beat again for 5 minutes on high.
Fill cupcake liners 2/3 full, and then bake the cupcakes for 12-15 minutes, or until a toothpick or cake tester inserted in the center comes out clean.
Move to a rack to cool until you can pop out the cupcakes, then place these on a baking rack with aluminum foil underneath.
Juice the two limes, measuring the amount of liquid produced. Generally, you should get around 1/4 c of lime juice. Add the triple sec, tequila, and sugar to a saucepan and heat over medium high heat.
Stir until the sugar has dissolved and remove from heat. Brush over the top of warm cupcakes, being generous.
Allow cupcakes to finish cooling, then frost as desired.