Combine the warm water and yeast and let it sit for 10 minutes. Add the starter, flour, and salt to a mixing bowl and pour in the yeast mixture. Knead the mixture for 5 minutes, or until it forms a sticky dough.
Place the dough in a greased bowl and cover it with plastic wrap. Let the dough rise for 45 minutes.
Gently deflate the dough and grab an edge and stretch it to the center multiple times. Cover the dough and let it rise for 45 more minutes.
Place the dough on a lightly floured surface and punch out the air. Divide the dough into 2 even pieces. Shape each piece of dough into a round ball and cover each with plastic wrap. Let the dough rest for 30 minutes.
Flatten one piece of dough, then fold it in half lengthwise. Turn the dough 180 degrees and repeat the process until the dough is longer.
Roll the dough into a 16 inch long log. Shape the ends into a pointy shape. Repeat the shaping process with the remaining piece.
Place the dough on a prepared baking sheet, seam side down. Cover the baguettes with a towel and let them rise for 45 minutes to 1 hour, or until they are light and puffy.
Preheat the oven to 450º F.
Make some 45 degree angle cuts on the top of each baguette using a sharp knife or razor. Place an oven-safe pan on the bottom rack of the oven and boil 1 1/2 cups of water.
Place the baguettes in the top rack of the oven. Pour the boiling water into the hot pan and quickly close the oven.
Bake the baguettes for 20 to 25 minutes, or until they are golden brown. Open the oven 2 inches and leave the baguettes for 30 minutes to develop a crust.
Remove the baking sheet from the oven and let the baguettes cool on a cooling rack. Serve the baguettes fresh or reheated.