For the currant vinegar, put the vinegar in a saucepan with the currant. Add the brown sugar and bring everything to a boil.
Simmer for about 1 minute and then remove from heat. Pour the vinegar through a fine sieve into a second pot. The juice of the currant collected in the sieve can be squeezed out with a spoon or ladle.
Pour the currant vinegar into a bottle and store in the refrigerator.