Prepare the rim: On a small plate, mix together the granulated sugar and freshly grated lemon zest. Rub them together with your fingers to release the aromatic lemon oils. Run a lime or lemon wedge around the rim of your rocks glass, then dip it into the lemon-sugar mixture until coated.

Fill the prepared rocks glass with fresh ice and set it aside.

In a cocktail shaker, combine the tequila, limoncello, cream of coconut, and fresh lime juice.

Fill the shaker generously with ice, secure the lid, and shake vigorously for 15 to 20 seconds until the outside of the shaker is frosty and cold.

Strain the mixture into your prepared glass over the fresh ice.

Garnish with a fresh lime wheel or a twist of lemon peel, and enjoy immediately!