Mix all together, place in a sealed container or jar and let stand at room temperature (warm) for about 24 hours.
You will end up with 100g of a “paste” after this time. Discard ½ of it leaving 50 g of paste and repeat the recipe again, adding 50 g of flour and 50 g of water to it. Mix well and let stand for another 24 hours, covered.
Discard all but 50g again and repeat feeding once a day for about 7-10 days, and you should have a viable starter culture.
Maintain at slightly above room temperature for extended periods of time or keep in the fridge for inactive periods of baking.
Notes
Makes 100-150g of fresh sourdough starter (will grow each active day)