In a large bowl, dissolve yeast and warm water. Allow to sit for 6 to 8 minutes until water is foamy.
Add salt and vinegar. Mix in flour a cupful at a time until it's all incorporated. Dough will be slightly wet.
Cover your dough with a tea towel and set it on top of the fridge (or a draft free warm place) to rise for about 2 to 3 hours, or until the dough has at least doubled in size.
Cover dough (make sure it can still breathe, don't seal completely) and place in fridge for 8 hours.
Take 1/2 of the dough (or 1/3 for a smaller loaf) out of the bowl, it’s very wet, so lightly flour your hands, and pull it into the shape of your loaf. Dust the top with flour and slash it with a sharp knife (flour keeps your blade from sticking) and let it rise for about 40 minutes.
Preheat oven to 450 degrees Fahrenheit with cast iron Dutch oven inside.
Remove dutch oven from stove and carefully place one loaf into Dutch oven. Cover with the lid and bake for 25 minutes, remove lid and bake for another 10 minutes until golden on top. (No cast iron Dutch oven, see notes for alternate baking instructions)