This drink starts with a simple shrub--a tart, fruity liquid you make ahead and can also sip straight up or with seltzer-made with sugar, vinegar, citrus, and a tea bag. It's a play on a Greyhound (grapefruit juice and vodka). Salt the rim if you like.
Rim the martini glass with salt, if desired.
The shrub recipe makes 2 cups, enough for 8 drinks or cocktails. It keeps up to 3 weeks, chilled. Nutrition data for this recipe includes the full amount of shrub. The actual amount consumed will vary.