To make the dough: In a large bowl, add the yeast and warm water and stir to combine. Let sit for 5 minutes or until bubbly.
Add the flour, sea salt, and cold water and mix the dough with your hands just until it’s mixed. It should feel wet and look shaggy. Cover with plastic wrap, and let it sit for 12 hours. (I usually make this dough at night, then plan to roll it out the following morning).
Line a baking sheet with parchment paper.
To roll out the dough: Lightly flour around the sides of the bowl and pull the dough out onto a lightly floured surface. You can add a bit of flour on top of the dough too. Divide the dough into three equal portions.
Create a ball with a smooth top by pulling and tucking the dough under itself. Turn it seam side up, then fold two of the sides into the middle and pinch the seam shut, it will be a rectangle shape at this stage.
Flip it so it is seam side down. And gently, with the palms of your hands, roll the dough out until it is about 14-inches in length. Transfer it to the prepared baking sheet. Repeat with the other two pieces of dough.
Cover the baking sheet with a kitchen towel, and let it sit for 1 hour.
Preheat the oven to 550°F.
Score each baguette by taking a razor blade (or sharp knife) and cutting slits on a diagonal, you should have about 5 to 6 scores on each baguette.
Bake for 12 minutes or until golden brown.