With a microplane, zest the grapefruit, then juice it, adding the juice to the zest. Add an equal volume of sugar, and shake to dissolve. Once fully incorporated, let it rest overnight before straining it off into a clean jar.

Combine your tequila, lime juice, and grapefruit syrup in a shaker, and give everything a quick shake before straining over fresh ice and topping with club soda. (If youre using a pre-made soda, feel free to just mix your drink taste.)

Typically its made with grapefruit soda, but Im a fan of making my own sodas using fresh fruit syrups and club soda. It takes only a little extra planning, and its well worth the effort. Zest a grapefruit (if you can find white grapefruit, use it -- this slightly more bitter and funky variety holds up better to being made into a syrup) then juice it, and add the juice to the zest. Stir in an equal volume of sugar, and shake the mixture to dissolve. (Recruiting a friend helps.) Avoid heating the mixture to speed up the process, since heating it will replace the bright fresh flavor of the grapefruit with a darker candied flavor; think of the difference between a fresh orange and marmalade. Heating will also extract more bitterness from the zest, which is not what we want in the finished product. Let it rest overnight, strain it the next day, and you've just made a non-alcoholic grapefruit cordial. This same method can be applied to any citrus -- just add club soda, and youve got yourself a fruit soda.