A classic gin sour—that’s just gin, fresh lemon juice, and sugar shaken together—is refreshing on its own, but also adapts to any number of other flavors. Adding a big dose of fruit liqueur would take over the drink, drowning out the lemon and leaving it too sweet. But a quick rinse brings in the suggestion of that fruit flavor, strong on the nose and elusive on the tongue. Here, we’re using the grapefruit liqueur pamplemousse, but any fruity or floral liqueur would work: blackcurrant Cassis, elderflower St-Germain, pomegranate liqueur, or even an orange liqueur like Combier, Cointreau, or Curaçao. It’s a great way to play around with those random bottles you’ve been collecting that are too sweet to drink on their own.