In a large bowl, mix warm water, yeast, and sugar. Let sit for 5-10 minutes until frothy.
Add salt and 3 cups of flour, stirring until combined. Gradually add remaining flour (½ cup at a time) until the dough pulls away from the bowl.
Turn dough onto a floured surface and knead for 5-7 minutes until smooth and elastic.
Place dough in a lightly oiled bowl, cover with a towel, and let rise in a warm place for 1 hour or until doubled in size.
Punch down dough and shape into a 12-inch log (or two smaller loaves). Place on a parchment-lined baking sheet.
Cover with a towel and let rise for 30 minutes. Preheat oven to 375°F (190°C).
Score the top of the loaf with a sharp knife.
Bake for 20-25 minutes until golden brown and hollow-sounding when tapped.
Transfer to a wire rack and cool for 10 minutes before slicing.