Put the warm water in the bowl of a stand mixer and add the yeast.
Add sugar and let the mixture stand for 5 minutes to proof.
Set the bowl on a scale, set tare to "0" and add 80 to 120 grams of discard. Use 80 grams for less sourdough flavor and up to 120 if you like a lot.
Give it a stir and then add salt and 135 grams (1 cup) bread flour. If you added the smaller amount of discard, add 2-3 tablespoons more water.
Continue stirring until you have a clumpy, shreddy, dough. Set on the mixer stand and knead with the dough hook for about 5 minutes.
After kneading, the dough should be supple and cling to the hook and to the bottom of the bowl only. It should not be sticking to the sides of the bowl. If for some reason it is very dry, add 1-2 more tablespoons of water and knead for a few more minutes. If it is loose and extremely sticky, you can add a tablespoon or two of flour and knead again.
Grease a 1 ½ quart bowl with olive oil and scrape the dough into the bowl. Using a heavy duty scraper, Scrape around the sides, folding it over on itself and shaping it into a ball. It will spread out again, but that's okay. Cover and let rise for about an hour.
Once dough has risen, scrape it out of the bowl onto a piece of parchment, then set the parchment and dough back in the bowl for the second rise. This second rise should only take about 30 minutes with the instant yeast.
Meanwhile, put a lidded Dutch oven in the oven and preheat to 450F.
When the dough has risen, use a razor or knife tip to make a small slash in the top of the dough. Remove the hot Dutch oven from the oven, and plop the dough ball with its parchment paper into the Dutch oven. Close and put in the oven. Bake for 25 minutes at 450, then remove lid and bake for about 20 minutes at 375F. If it doesn't seem done, continue baking until the outside is golden brown. You can also test with a meat thermometer. If it registers over 205, it's done.
Let cool for about an hour before slicing.
Notes
For a single rise loaf, increase the yeast just a tad -- about ⅝ of a teaspoon. Proof it in the water (even if using quick rising), then add the sugar, 120 grams of discard, salt, bread flour and the olive oil. Knead until very soft and smooth, then let rise in a parchment lined bowl for about 45 minutes while you preheat the Dutch oven. Bake with the lid on at 450 for about 25 minutes, then lid off at 375 for another 20 minutes or until golden brown.