Shrubs (drinking vinegars) may sound a little out there, but the combination of tangy vinegar with juicy fruit is fantastically refreshing. They brighten up any cocktail they touch, or they can stand on their own with just a bit of soda water. You don't even need a recipe: just remember "1:2:2."
There are a few different ways to make a shrub, but we're going to focus on the "cold" method, which doesn't require a stove. You'll need 1 pound of fruit, 2 cups of sugar, and 2 cups of vinegar. Sprinkle the sugar over your chopped (and maybe slightly smushed) fruit and cover with a dish towel. You could even throw some herbs or spices in for good measure. Leave it on the counter for a couple of days, and when you come back, you will find fruit that is positively swimming in its own juice. Strain and mix the syrup with any vinegar of your choice (Food 52 recommends cider vinegar), but keep in mind that more acidic fruits will need less vinegar than something sweet like melon.
Your shrub is now ready to be stored in the fridge, where it will keep for at least a month, or poured over ice and topped with bubbly soda water. (Or, you know, actual bubbly. Also gin.)