Extra-Tangy Sourdough Breead

1) Combine the starter, water, and 3 cups of the flour. Beat vigorously for 1 minute.
2) Cover, and let rest at room temperature for 4 hours. Refrigerate overnight, for about 12 hours.
3) Add the remaining ingredients: 2 cups of flour, sugar, salt, and sour salt, if you're using it. Knead to form a smooth dough.
4) Allow the dough to rise in a covered bowl until it's relaxed, smoothed out, and risen. Depending on the vigor of your starter, it may become REALLY puffy, as pictured; or it may just rise a bit. This can take anywhere from 2 to 5 hours. Understand this: sourdough bread (especially sourdough without added yeast) is as much art as science; everyone's timetable will be different. So please allow yourself to go with the flow, and not treat this as an exact, to-the-minute process.
5) Gently divide the dough in half.
6) Gently shape the dough into two oval loaves, and place them on a lightly greased or parchment-lined baking sheet. Cover and let rise until very puffy, about 2 to 4 hours. Don't worry if the loaves spread more than they rise; they'll pick up once they hit the oven's heat. Towards the end of the rising time, preheat the oven to 425u0b0F.
7) Spray the loaves with lukewarm water.
8) Make two fairly deep horizontal slashes in each; a serrated bread knife, wielded firmly, works well here.
9) Bake the bread for 25 to 30 minutes, until it's a very deep golden brown. Remove it from the oven, and cool on a rack.