1 teaspoon freshly grated ginger
1½ to 2 teaspoons Japanese plum drinking vinegar (known as ume, found in most Asian markets)
1 umeboshi (salted plum)
vodka, gin, or bourbon (optional)
Put the freshly grated ginger into a chilled mason jar or 16-ounce glass. Add the plum drinking vinegar and umeboshi (and spirit, if desired). Fill the glass halfway with ice and top with ginger ale. Using a long spoon, mix vigorously until well-combined and frothy. Serve immediately.
*For a less sweet version, Jensen recommends soda water.