Step 1

Place 1 1/2 cups water and 2 tablespoons butter in a heat safe bowl and microwave until hot (125°F to 130°F). Set aside.

Step 2

Combine flours, yeast, salt, and 1 tablespoon sugar in food processor and blend (using dough blade or regular blade). With machine running, gradually pour butter and hot water through feed tube, adding enough liquid to form smooth elastic dough. Process 1 minute to knead.

Step 3

Grease a large bowl with butter. Add dough to bowl, turn to coat. Cover bowl with plastic wrap, then a towel; let dough rise in a warm draft-free area until doubled in volume, about 1 hour.

Step 4

Prepare a baking sheet by covering with parchment paper. Set aside.

Step 5

Punch dough down and knead on lightly floured surface until smooth. Divide into 8 pieces. Form each dough piece into ball (about 5 ounces each). Place dough balls on prepared sheet, flattening each slightly. Using serrated knife, cut X in top center of each dough ball. Cover with towel and let dough balls rise until almost doubled in volume, about 1 hour.

Step 6

Meanwhile: Preheat oven to 375°F. Prepare another baking sheet by covering it in parchment and sprinkling it with cornmeal. Set aside. Prepare and set aside beaten egg.

Step 7

Bring 8 cups water to boil in an 8 quart pot, . Add baking soda and 2 tablespoons sugar (water will foam up). Add 4 rolls and cook 30 seconds per side. Using slotted spoon, transfer rolls to prepared sheet, arranging X side up. Repeat with remaining rolls.

Step 8

Brush rolls with beaten egg. Sprinkle rolls with coarse salt. Bake rolls until brown, about 25 minutes. Transfer to cooling rack and cool 10 minutes. Serve rolls warm or room temperature.