In a large bowl, combine the water and starter. Mix well.
400 grams bubbly and active sourdough starter, 1 1/3 cups (330g) lukewarm water
Add the sugar, honey, oil, salt, and 6 cups of the flour, stirring well to evenly moisten.
1/3 cup (67g) granulated sugar, 2 Tablespoons (42g) honey, 1/4 cup vegetable or canola oil, 2 teaspoons (18g) salt, 6 to 7 cups (846g to 987g) bread flour
Knead the dough in a mixer fitted with a dough hook attachment for 6-8 minutes until smooth (around 10-12 minutes if kneading by hand). The dough should be soft and tacky but not too sticky, and it should pass the windowpane test. Add the reserved flour a little at a time as needed while kneading if it the dough is sticking to the sides of the bowl a lot.
Transfer the dough to a lightly greased bowl and cover with a kitchen towel or a piece of plastic wrap. Let the dough bulk rise at room temperature (around 68℉ to 70℉) until it fills the bowl and has risen until not quite double in size, around 10-12 hours. If your dough hasn't risen much, try placing it in a warmer spot for another hour or two. At this point, you can shape the loaves or just stick the bowl of dough into the fridge for a long cold bulk rise overnight or up to 18 hours before shaping the dough then proceeding with the second rise and normal bake.
Lightly grease two 8.5x4.5-inch loaf pans with butter or spray with baking spray. Divide the dough into two equal portions. Gently press half of the dough into a rectangle about 8x12-inches wide. Roll the dough into a log on the short side, tucking the ends under to shape the loaf, then transfer it to a prepared pan with the seam side down. Repeat with the remaining dough.
Cover the loaves with a kitchen towel or a loose piece of plastic wrap and let rise at room temperature until puffy and risen over the edges of the pan, around 4-8 hours. If you press a finger into the dough, it should leave a little indentation instead of springing back immediately when the loaves are ready to bake.
About 30 minutes before baking, preheat the oven to 375℉ (191℃). Bake for around 40-45 minutes or until the loaves are golden brown and hollow sounding when thumped. An instant read digital thermometer should read 190℉ when inserted into the center of a loaf.
Immediately rub the top of each loaf with some softened butter while hot, then let cool in the pan for 10 minutes before turning the loaves out onto a wire rack to cool completely before slicing.
Store for up to 3 days in a plastic bag at room temperature or freeze for up to 2 months.