Put 1/2 cup flour and 1/2 cup water into a wide mouthed glass jar and mix it well. Cover loosely and keep it aside for about 24 hours. Cut each grape into half and stir it into the flour water mixture.

The next day your Starter should show signs of a bubbled surface and having risen in volume. Mix in another 1/2 cup of flour and 1/2 cup of water. Cover loosely and let it sit for another 24 hours.

On the third day, you can remove what is left of the grapes if you want. Otherwise it will eventually dissolve in the Starter. Feed the Starter this time with 1/4 cup flour and 1/4 cup water. I reduce the amount of the feed so that I do not over fill my jar and have to discard. If your jar is filling up you can discard 1/2 cup of Starter and then feed with 1/2 cup flour and 1/2 cup flour.

Let it sit for 12 hours and the feed the Starter again with another 1/4 cup flour and 1/4 cup water.

On the fourth day, once again feed it with 1/4 cup flour and 1/4 cup water. Usually, after about 6 hours my Sourdough Starter is ready and active enough to be used. It should have a pleasant, slightly tangy and almost sweet smell. Refrigerate at this point if not using the Starter right away.

If your Starter throws up any hooch at any point, just discard it and carry on feeding it as usual. If the mixture turns a different colour (orange or pinkish) at any point or smells bad, THROW IT OUT. Start out fresh.