Preheat the oven to 350 degrees . Line 2 cupcake pans with baking liners. Using an electric mixer, beat 2 sticks butter and the granulated sugar until creamy. Gradually beat in the eggs, egg white and oil. Scrape down the sides of the bowl and mix again.
In a medium bowl, whisk together the flour, baking powder, baking soda and 1 teaspoon salt. In a large glass measuring cup, stir together the milk, 2 tablespoons lime juice and 1/2 teaspoon vanilla extract. On low speed, mix in one-third of the wet mixture, then one-third of the dry mixture. Repeat twice, ending with the dry mixture. Mix in half of the grated lime peel.
Fill each baking liner about three-quarters full with batter. Bake until the cupcakes spring back when gently touched, about 25 minutes. Let cool completely, about 30 minutes.
Meanwhile, using the electric mixer, beat the remaining 1 stick butter until creamy. Beat in 1 cup confectioners' sugar. Beat in the tequila, and the remaining 2 tablespoons lime juice, 1/2 teaspoon vanilla, lime peel, 1 teaspoon salt and the food coloring until smooth and creamy. Beat in the remaining 1 1/2 cups confectioners' sugar one-third at a time, until just soft enough to spread.
Spread the frosting on the cooled cupcakes. Add the sugar crystals to a bowl; lay each frosted cupcake on its side in the bowl and gently rotate to form a rim of sugar. Top each cupcake with a lime wedge candy.