Line a large baking sheet with parchment paper and sprinkle evenly with cornmeal. (Greased baking sheets work too, but we prefer the cornmeal method.) In a small bowl, dissolve yeast in warm water.
In the bowl of a stand mixer, combine hot water, oil, sugar, salt, and 3 cups of flour. Mix with the paddle attachment.
Add yeast mixture and mix to combine.
Switch to the dough hook attachment and add the remaining 3 cups of flour 1 cup at a time, mixing after each addition. Mix until the dough is smooth and pulls together around the paddle. NOTE: Watch the dough, not just the flour amount. The finished dough should be soft, smooth, and slightly tacky but should not leave a lot of dough on your fingers. Add extra flour a little at a time only if needed. Once all of the flour is added, let the dough rest for 15-30 minutes.
Place dough onto a lightly floured surface and divide into three pieces. Roll each piece into a 9x12-inch rectangle. Roll each rectangle tightly from the long side, pinch the long seam closed, and tuck the ends underneath so the loaf stays even and holds its shape.
Place each dough roll on a prepared baking sheet, seam side down.
Score the bread across the top 3 or 4 times (diagonal slashes will allow the bread to expand along those cuts without risking deflating a fully risen loaf.) Brush each loaf with beaten egg for a crisp and shiny crust. Let dough rise in a warm place, uncovered, for about 30 to 45 minutes, or until noticeably puffy. For a softer crust: Skip the steam and brush the hot loaves with melted butter as soon as they come out of the oven.
Toward the end of the rise, preheat the oven to 375°F.
Bake for about 20 minutes, or until deeply golden and the loaf sounds hollow when tapped on the bottom.
Let cool slightly, then slice with a serrated knife and serve warm.