Boil all the tools (including the jar) to sterilize. Put the raisins in the sterilized jar, then add water.
Add sugar, then stir with a sterilized spoon. Loosely cap the lid. Open the jar once or twice a day and stir with a spoon.
While it depends on the temperature, in about 2 to 3 days, small bubbles will form around the raisins, and the raisins will begin to rise. The water will also become cloudy.
When the liquid starts to fizz, and all of the raisins have rose to the top, it's ready! It will smell nice, like wine.
Filter the fermentation liquid, make starter dough, then use it.
Without using sourdough starter, you can make bread directly from the fermenting liquid. Baguette Made with Homemade Yeast (directly from Fermenting Liquid): Recipe ID: 983484.
French Country-Style Bread (le pain de Campagne) Made with Homemade Bread Starter (Recipe ID: 859009).
Baguette Made with Homemade Bread Starter (Recipe ID: 983484).
Story Behind this Recipe
I can't forget how moved I was when I tried some bread made with homemade starter, so I started making it myself.
If the smell is unpleasant, then, without a doubt, toss it out. Since raisins have a high sugar content, the yeast will ferment without any additional sugar. Fermentation time depends on the temperature; in the winter, store the jar in the warmest location possible.