Wash mint; place in a sterilized wide-mouthed jar. Bruise mint leaves, using a wooden spoon. Pour vinegar over sprigs in jar. Cover with a metal lid, and screw band tight. Let stand 10 days; shake jar daily.
Strain vinegar through 4 layers of cheesecloth into a decorative bottle, discarding mint residue. Seal with a cork or other airtight lid. Use in meat sauces and salad dressings.