1. In a large bowl, stir together 1 1/2 cups warm water (100˚F) and 1/2 Tbsp of salt. Sprinkle the top with yeast and let it sit 2 min, then stir.
2. Measure out exactly 3 1/4 cups of flour and add flour to the bowl. Using a spatula, stir until dough comes together and is well blended. Cover the bowl with plastic wrap and let it rise at room temperature 2 hours (or about 2-3 times in volume).
3. Line a cutting board with parchment paper and generously dust with flour. Scrape dough out of the bowl with a spatula onto the floured surface.
4. With well-floured hands, fold dough in half, then fold in half again. Dust dough generously with flour, lift it up and form a ball in your hands. Sprinkle parchment paper with more flour or cornmeal, extending about 1" past the border of the dough since it will expand. Place dough over the flour, seam side down, and let it rise uncovered at room temp 40 minutes.
5. Meanwhile, prepare your oven with 2 racks - one rack in the middle for the bread and one rack on the bottom for the water pan. Place a rimless cookie sheet (or use the backside of a rimmed cookie sheet or pizza stone) on the center rack. Preheat the oven and cookie sheet to 450˚ F. Also heat up 1 cup water.
6. Just before baking, score the top of the bread 3 times. Place a metal or cast iron dish (never a glass dish*) on the bottom rack with 1 cup hot water (being careful to not splash water on a glass oven door). Slide the dough with the parchment paper onto the hot cookie sheet and bake at 450˚ F for about 25-28 min or until golden brown. Transfer loaf to a rack and cool to room temp before cutting into it.
*CAUTION: DO NOT USE A GLASS DISH on the bottom rack to hold water, or it may explode when you add water; just trust me on this one. Also, be careful not to splash water on the glass door of your oven to prevent shattering with strong temperature change.