Cream butter and superfine sugar together until fluffy. Add the egg and mix well. Add the lime zest, orange liqueur and tequila, mix well. Whisk together the flour and salt. Add to the mixture slowly. Add the food coloring and mix well. Divide cookie dough in half and place in wax paper. Rolling out to form a log, repeat with the other half. Refrigerate 2-24 hours.

Preheat oven to 350F. Whip the egg and paint the logs and then roll in a sugar/salt mixture (2/3 sugar and 1/3 salt). I mixed about 2 Tbsp. sugar and 1 Tbsp. salt together to coat each roll but do it to taste if you don't like it too salty. Use your finger to press the mixture onto the dough, you just need an even coating. Slice 1/4" thick and place on a parchment or cookie liner on a baking tray an inch or so apart, they do spread. Bake for 12-15 min until edges are light golden brown. Let cool 5 min. on the tray and then move to a cooling rack to fully cool.