Whisk flour, yeast, and salt in a large bowl.
Pour in warm water and stir until a shaggy dough forms with no dry bits.
Lightly oil the bowl if using. Cover tightly and let rise until doubled, 1 1/2 to 2 hours.
Dust the counter with flour. Scrape out the dough and fold it into a tight ball.
Set the dough seam-side down on parchment or a floured towel. Rest 30 minutes.
Place a Dutch oven with its lid in the oven and preheat to 450°F for 30 minutes.
Sprinkle cornmeal into the hot pot. Lower in the dough, score the top if you like, and cover.
Bake covered for 30 minutes, then uncover and bake 12 to 18 minutes until deeply golden.
Transfer to a rack and cool at least 1 hour before slicing.