In a small bowl, combine warm water, sugar, and yeast. Stir gently and let sit for 10 minutes until frothy.

In a large mixing bowl, combine 3 1/2 cups flour and salt. Add the yeast mixture and melted butter. Mix until a dough forms, adding the remaining flour if needed to form a dough that isn't very sticky.

Turn the dough onto a floured surface and knead for about 6-8 minutes until smooth and elastic.

Place the dough in a greased bowl, cover with a damp cloth, and let rise in a warm place for 1 hour or until doubled in size.

Punch down the dough, then shape into a loaf and let rest for 10 minutes. Preheat oven to 425°F.

Bring 2 1/2 quarts of water to a boil and add baking soda. Boil the loaf for 30 seconds per side, then place on a baking sheet.

Sprinkle loaf with coarse salt and bake for 25-30 minutes or until golden brown.