Rinse and drain fresh berries. Add fresh or frozen berries to the jar. Pour in vinegar, cover tightly. Store in a cool dark place (between 60º to 80º F) undisturbed for 3 to 4 weeks. Pour through a fine-mesh strainer that is lined with cheesecloth. Store finished fruit vinegar in the refrigerator for 2 to 3 months. Use in salad dressings to replace other vinegars for fresh, original flavors.