Pack herb leaves into a clean 1-quart jar with a tight-fitting lid. Using a muddler or the end of a wooden spoon, lightly bruise the herb leaves to release their essential oils.
In a medium saucepan bring vinegar to simmering. Pour hot vinegar over herb leaves. Let cool to room temperature. Seal jar; shake well. Let stand at room temperature for 2 weeks, shaking jar every day.
Strain vinegar mixture through damp, 100%-cotton cheesecloth. Transfer to two clean 12-ounce bottles. Store vinegar in the refrigerator for up to one year before using.