Combine raspberries and vinegar in a sterilized glass jar with an airtight seal. Leave in a warm place to steep, shaking jar occasionally.
After 2 weeks, strain vinegar from raspberries using a fine strainer. Press raspberries gently to extract flavor.
Add vinegar and sugar to a saucepan. Over low heat, simmer for 10 minutes.
Transfer to sterilized jars or bottles. If desired, place a few ripe berries in the bottle.Servings: 2 cups