In a large mixing bowl, add yeast to warm water. Then add the Sourdough Starter, oil, sugar, and salt. Mix well and then add enough flour to create a soft dough.
On a floured surface and gently knead 20-30 times with flour. Turn dough into a greased bowl and cover. Once you see the dough's size has doubled, 1 to 1-1/2 hours later, it is ready to use.
It is time to preheat the oven to 400°. Take the dough and punch it down. On a floured surface turn the dough and divide it in half. Roll each half into a 12×8-inch rectangle. Roll up the dough, starting at the long side and sealing it with your fingers. Place the rolls seam-side down on two greased baking sheets and let them rise until they double in size, about 30 minutes.
Slice the bread in 4 and make shallow diagonal cuts across the top. In a small saucepan, bring water and cornstarch to a boil. Cook and stir until thickened. Brush some on each loaf.
Bake loaves for 15 minutes then brush with remaining cornstarch wash, and bake 5-10 minutes longer. Let loaves cool on wire racks.
