I used to work at a bakery that made all of their bread fresh each day. The main bread, which was used for sandwiches, soup, croutons, toast, etc., was a sourdough baguette. I bet I made thousands of those baguettes – all form scratch and by hand – in the years I worked as a baker there.
The Baguette recipe in the MSBH is traditional baguette, not sourdough, although it does require a starter/sponge that is about a day old.
The MSBH recipe instructs that you keep the starter at room temperature but I can tell you from experience, this would have been a messy disaster for me. I kept mine in the refrigerator for about 24 hours. It still fermented just fine, but I avoided it growing too rapidly and spilling out of the container.
Once the dough is made (it’s a pretty straightforward process) and kneaded and left to rise and rise again, it’s formed into two long baguette loaves. The MSBH says to let them proof on a wooden peel and then be transferred to a baking stone in the oven, but given my track record in such endeavors, I just decided to let them proof on the same sheet they would bake on.
Once they’ve become light and airy, I scored them diagonally just before transferring them to the oven.
The oven does the rest!