Hi Gillian.

I never made my own vinegar, but I have very clear memories of my Grandma making her own. She used to put a slab of “mother” in a glass jug, then she would pour wine into the jug. She kept the jug in a dark room, covered most of the time, but she opened it for about a half hour every day. In a couple of weeks the “mother” settled to the bottom of the jug, while the vinegar above it was ready for use. I believe you could do something similar adding a cup of vinegar to the wine (if you do not have the “mother”).