If you can’t find white balsamic vinegar, substitute white wine vinegar and increase the sugar to 1 teaspoon.
- 1 teaspoon coriander seeds
- 8 scallions, thinly sliced
- 1/2 cup (or more) white balsamic vinegar
Toast coriander in a small dry skillet over medium heat until fragrant, about 1 minute. Let cool, then grind in a spice mill or finely chop.
Combine scallions, salt, sugar, and coriander in a small bowl; let stand 20 minutes. Add vinegar, adding more if needed to just cover scallions. (Serve alongside oysters.)