Combine bread flour, 1 envelope yeast, 1 teaspoon salt, 1 teaspoon sugar and celery seeds in food processor and blend. With machine running, gradually pour hot water through feed tube, adding enough water to form smooth elastic dough. Process 1 minute to knead. Grease medium bowl. Add dough to bowl, turning to coat. Cover bowl with plastic wrap, then towel; let dough rise in warm draft-free area until doubled in volume, about 35 minutes.
Flour baking sheet. Punch dough down and knead on lightly floured surface until smooth. Divide into 8 pieces. Form each dough piece into ball. 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 20 minutes.
Preheat oven to 375°F. Grease another baking sheet and sprinkle with cornmeal. Bring 8 cups water to boil in large saucepan. 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.
Brush rolls with egg white glaze. Sprinkle rolls generously with coarse salt. Bake rolls until brown, about 25 minutes. Transfer to racks and cool 10 minutes. Serve rolls warm or room temperature. (Can be prepared 6 hours ahead. Let stand at room temperature. Rewarm in 375°F oven 10 minutes.)