How to soak raisins in vinegar:
1. Take about ten tablespoons of raisins and put the raisins into a sealed container such as a glass bottle.
2. Pour the vinegar into the container where the raisins are placed until the vinegar covers the raisins.
3. Sealing. As long as it is marinated overnight, the vinegar will penetrate into the raisins and cause them to swell. One tablespoon a day is enough.