In a large bowl, combine 3 cups very hot tap water with butter, sugar, and salt. Stir until butter melts; let cool until warm (110� to 115�). Stir in yeast; cover and set in a warm place until bubbly, about 15 minutes.
Add 5 cups of the flour. Beat with a heavy-duty mixer or spoon just until batter is stretchy, 2 to 5 minutes. Mix in enough of the remaining flour, about 3 1/2 cups, to form a stiff dough.
Using a dough hook beat on medium speed until dough pulls from side of bowl and no longer feels sticky, about 5 minutes. If required, add more flour, 1 tablespoon at a time.
Cover bowl with plastic wrap and let dough rise in a warm place until doubled, about 1 1/2 hours.
Meanwhile, if using a 5-quart cast-iron Dutch oven, cut a circle of foil to fit bottom of pan; put foil in pan. Rub the foil and sides of pan generously with salad oil. A nonstick pan that is not worn needs no preparation.
Knead dough with dough hook or on a floured board to expel air; then form into a smooth ball.
Place dough in baking pan. Cover loosely with plastic wrap and let rise in a warm place until almost doubled again, 45 minutes to 1 hour; watch closely so it doesn't rise too much.
Preheat oven to 350F�.
Place in preheated oven, uncovered and bake until loaf is golden brown and sounds hollow when tapped, 50 to 55 minutes.
Remove bread from oven and invert onto a rack (you'll need a helper); remove foil and turn loaf right side up. Cool at least 45 minutes. Serve warm or cool, cut into wedges.