How to Make Vinegar in 4 Steps

1. Create a sweet, fermentable base.
Use overripe fruit or vegetable scraps, leftover compotes or jams, fermented juice, wine, and a few fruit peels — they contain natural yeast. Add filtered or spring water to a clean vessel. Add a little sugar if needed; the mixture should taste mildly sweet so the yeast has something to eat. Add a splash of leftover wine, cooking wine, or a bit of whatever alcohol is in your cabinet to start the process.
Note: if the mixture is already sweet from jam or very ripe fruit, you can omit or reduce the sugar in the calculator. You can also add peels of fruits or vegetables for natural yeast — pineapple skins, grapes, apples, pears, citrus, and even cabbage leaves (which are loaded with yeast, explaining why they ferment so easily).

2. Let it ferment into alcohol.
Cover with a breathable lid and let natural yeasts do their work. I use kitchen linen or a paper towel secured with a rubber band. This first stage takes 5–10 days depending on temperature. Look for bubbles and light fizzing — signs the sugars are turning into alcohol. Stir for the first few days so everything stays submerged; otherwise, you may grow kahm yeast. It’s safe but not cute, and it can muddy the color.

3. Introduce oxygen and time.
Once the bubbling slows, strain the liquid and transfer it to a wide jar. Add a vinegar mother or a generous splash of raw vinegar. Cover loosely again with linen or a paper towel so oxygen can circulate — oxygen is what allows the alcohol to convert into acetic acid.

4. Age until it tastes like vinegar.
Let it sit for 3–6 months, sometimes longer. Taste biweekly or monthly to track its progression. When it’s bright, tangy, and rounded, strain again and bottle. It will continue to mature with time. If you don’t trust your judgment, buy an acid tester or taste it next to a store-bought vinegar.