Give your sourdough starter a good stir before adding it to the bowl. Separation is natural and common.
In a large mixing bowl, combine water, sugar, sourdough starter, oil, and 1 TBS instant yeast. Leave it for about 10 minutes, or until the yeast is active and foamy.
Once the yeast is active, add in the salt, and about 5 cups of bread flour. Mix together well. Slowly add in the last cup of flour.
The dough will be slightly sticky, but should pull away from the bowl and hold a soft round shape.
Quickly remove the dough from the bowl and spray it with cooking spray. Place the dough back in the bowl to rise. Cover the bowl with plastic wrap that has also been sprayed with cooking spray. This prevents any air draft drying out your dough. The spray wrap will prevent the dough from sticking once it has risen.
Let the dough rise in a warm place until doubled in size. I will usually preheat my oven to about 120, turn it off, and stick it in there.
Once the dough has risen, it’s time to shape your loaves. I prefer to use medium sized aluminum loaf pans. You can buy a 3 pack for .98. It’s the perfect size. Divide the loaves into 4 equal sizes. Shape into a loaf and place in a greased pan.
Cover again with greased plastic wrap and let rise in a warm space for another 1-2 hours, or until it just at the top of the pans.
Preheat oven to 350 degrees and bake for 30 minutes.
Immediately remove from pans onto a cooling rack, and brush the tops with melted butter.