Take the yeast out of the fridge and let it sit in the closed jar for at least 2 hours to double in size.
Open the jar and refresh it: add an equal amount of flour, and 50-100% of water, depending on what it will be used for. (50-60% for bread, 70% for pizza dough.) (Or 70% seems to be ok in general)
First mix in lukewarm water slowly with spatula, then stir in flour.
Suppose we plan to make pizza and we have 250g of starter, to which we add 250g white flour and 175ml water (70%).
Separate into portions of 100 - 200 g.
Divide the starter into three jars (one small, two large), for
Push down dough with wet fingers and mark level of dough in jar with elastic band.
Leave the jar #1 with yeast to use open for four hours. (It should double in size.) Leave the other two jars open for two hours, and then close them and put in the fridge.
Let rise for two hours and then keep in fridge. Keep at least one portion in reserve in fridge.
Dough to be used should be kept out and must at least double in size (~4 hours).
NB: This procedure assumes the discard is also refreshed. In other recipes it is not. Instead you refresh what you need and “discard” the rest (or use it where you want). Alternatively you take out what you need, and replace it with half flour and half water to refresh the starter.
Sample amounts
120 -> 320