In large stainless or pottery bowl, add 1 cup sourdough discard and 1 cup sourdough starter
If using all starter, use 2 cups discard instead of step 1
Add water and mix with discard/starter using dough whisk or wooden spoon
Only if you are using all discard, sprinkle in 1 tsp baker's yeast and mix in
Add white flour and 15 g salt
Mix thoroughly with dough whisk or spoon until everything is well incorporated
Let rise for 3-4 hours or until mixture has active bubbles. It will be very sticky.
If you are using all starter and baker's yeast, change the rising method to this: just let rise 60-90 minutes until you see bubbles or signs of yeast activity
Line 2 baking sheets with parchment paper. Pour 1/4 cup in two "puddles" on one of the baking sheets. If olive oil runs together, that's fine. Repeat with the second 1/4 cup of olive oil on the second baking sheet. When you put the dough on the sheets you will be wanting the dough to be squarely in the olive oil in two separate blobs per sheet. With wet hands, reach in bowl, grabbing about 1/2 of the mixture. Then, still in the bowl, take that half and grab half of that. Quickly remove it and plop it in center of olive oil puddle on baking sheet. It should move freely on the olive oil.
Do the same with the other three quarters of the dough, so you have two quarters on each baking sheet.
Let rest for one hour, uncovered. If you are using all starter and baker's yeast, let rest for only 20 minutes.
Place oven racks as follows: one high and one low.Preheat oven to 425°. Sprinkle rosemary leaves on the 4 rounds
With wet hands, gently put small dents in the 4 doughs with your fingertips. Drizzle the dough with about a tablespoon of extra virgin olive oil so the oil collects in the dents.
Sprinkle the 2 tsp of salt evenly all over on the 4 rounds
When oven is up to temperature, put one baking sheet on the top rack and one on the bottom. Bake for 15 minutes
Switch baking sheets (Top baking sheet to bottom rack, and vice versa)Bake for 15 more minutes, or until breads are golden brown on both top and bottom Let cool, and serve by letting people break off hunks, or cutting in wedges, or cutting in strips. The hunks and wedges work great for serving with soup and pasta dishes; the strips are good for appetizers.