Place yeast into the bottom of a large mixing bowl. Add water and stir, then mix in salt. Add flour and beat with a wooden spoon until dough is thick and sticky and pulls flour from the side of the bowl, 5 to 10 minutes.
Cover the bowl with plastic wrap and let stand in a turned-off oven until doubled in volume, 12 to 14 hours. Dough will be bubbly and very sticky.
Line a baking sheet with a silicone mat and dust generously with cornmeal.
Use a floured spatula to scrape dough out onto a well-floured work surface. Dust dough with flour. With well-floured hands, pat dough into a rectangle. Cut the rectangle into four equal pieces.
Dust one piece of dough with flour and stretch it with floured fingers into a log about 10 inches long and 1 1/2 inches around. Gently transfer to the prepared baking sheet. Wipe off excess cornmeal with a damp paper towel if desired. Repeat with another piece of dough. (Reserve remaining dough to bake later or prepare another baking sheet to bake all four loaves at once).
Dust loaves lightly with flour. Dust a large piece of plastic wrap with flour and drape it lightly over the baking sheet with the floured side down. Let loaves rise, covered, until doubled in volume, 1 to 1 1/2 hours.
Set the oven racks to the bottom and middle positions and preheat to 500 degrees F (260 degrees C) or as high as your oven will go. Place an oven-proof baking dish full of water onto the bottom rack of the oven.
Cut four or five angled slashes into the top of each loaf with sharp kitchen shears. Poke down any sharp tips of dough left by the scissors. Spray the loaves with water, using a spray bottle.
Bake in the preheated oven until baguettes are browned, about 15 minutes, spraying loaves with water after 5 minutes and 10 minutes. Turn the pan around on the second spraying.
Transfer baguettes to a cooling rack and let cool to room temperature before slicing with a serrated knife.