Idlis or dosas work on the same principle as sourdough bread, i.e. of cultivating the wild yeasts on or around a grain. But interestingly, unlike sourdough, the whole process of fermentation and doubling takes less than 24 hours. And unless it's really really cold, the method is almost fool-proof.
I wondered if ground urad dal or Vigna mungo (the component that makes idlis and dosa fluffy and sour) could be used to create a vigorous and quick wholewheat sourdough starter.
I do realise that the starter has an easier job with an idli or a dosa (the thickness varies from 3 inches to a few mm and there are no flavour expectations). But if the yeasts on urad are more active, there's a good chance of making a sourdough as quickly as a yeast bread.
I washed a handful of urad dal and soaked it in water.
After 12 hoursI ground it to a smooth paste, adding a tsp of water to ease the pulverisation.
I measured out 20 g of the urad paste into a plastic tub with a lid (so that I could throw the whole thing out without guilt, in case things got stinky and disgusting).
I added 20 g of wholewheat flour and 40 g of water to the urad paste, covered the tub and waited.
24 hours laterLots of tiny bubbles. The smell of fermentation, not particularly pleasant or sour, but not disgusting either.
I threw out all but a tsp of the starter and refreshed it with 20 g of wholewheat flour and 40 ml of water.
If there's progress by tomorrow morning, I might try to bake a small loaf with my new starter.