Bring wine to a boil in a saucepan over medium to high heat. Reduce the temperature to a simmer and cook until the liquid has reduced to about 1 to 2 tablespoons.

For each tablespoon of liquid that you have, add 1 cup of sea salt. Stir salt and if the liquid has not absorbed add an extra ½ cup and stir again. Spread salt onto a lined baking tray and leave out overnight to dry.

Transfer to a clean air-tight jar.