With the metal blade in place, add 3 cups flour, salt, sugar, butter and yeast to bowl of processor. Turn machine on and off rapidly 2 or 3 times or until butter is thoroughly cut into dry ingredients. Add half the water and turn processor on and off 4 times. Add 1 1/2 cups flour and remaining water. Repeat on/off turns 4 times, then let processor run until a ball of dough formson the blades. If the dough is too sticky (wet), add remaining flour a few tablespoons at a time. When correct consistency, let processor run 40 to 60 seconds to knead dough.
Turn dough out onto a lightly floured board and knead several times to form a smooth ball. Cover with plastic wrap and a towel. Let rest 20 minutes. Divide dough in half. Roll each half into an oblong 15 x 10 inches. Beginning at wide side, roll tightly Pinch seam to seal and taper ends by rolling gently back and forth. Place on greased baking sheets sprinkled with cornmeal. Brush dough with corn oil. Cover loosely with plastic wrap. Refrigerate 2 to 24 hours.
When ready to bake, remove from refrigerator. Uncover dough carefully and let stand at room temperature for 10 minutes. Make 3 ro 4 cuts on top of each loaf with edge of metal blade or sharp knife. Bake at 425 degrees for 20 minutes. Remove from oven and brush with egg white beaten with cold water. Return to oven and bake 5 to 10 minutes longer or until golden brown. Remove from oven and cool on a wire rack.