Gently place the raspberries in a sink of cold water to rinse. Carefully lift berries into a colander and allow to drain, picking out any debris as you go.
Clean and sterilize by dipping in boiling water a large, wide-mouthed glass jar with a lid.
Gently place raspberries in jar.
Heat the vinegar in a saucepan until warm but not hot.
Pour the warmed vinegar over the raspberries in the jar.
Allow to cool completely, then cover tightly.
Store in a cool, dark place for 12 days. Label with the date you started.
Strain the raspberries through a loosely woven muslin cloth or cheesecloth-lined colander into a very clean glass or plastic bowl. (Dip the clean bowl in boiling water before using.)
Using a sterilized funnel, pour the vinegar into sterilized bottles. Cork tightly. Store in a cool, dark place. Makes about 4 cups.