So it’s 3 days after I started making my initial sourdough culture and things are coming along really nicely. If your culture doesn’t look as bubbly as mine, then cover it up and leave it for another day or so, and if still nothing is happening, discard it all and start again.
When the aroma is pungent and acidic, and everything is bubbling away, the next thing to do is to feed your culture with fresh supplies. To do this, throw away just over 50% of the mixture and replace it with a handful of fresh flour (for me this is about 25g) and an equal measure of water. Stir to make a gloopy paste and leave again on the countertop, covered up.
Repeat this step on a daily basis for the next few days to refresh and build strength in your sourdough starter.