Bring 8 cups water, 1/2 cup baking soda and 2 teaspoons kosher salt to a boil in a pot. Cut 1 pound pizza dough into 6 pieces. Roll each piece into a 2-foot-long rope and pick up the ends to form a U shape; cross one end over the other twice to make a double twist in the middle; attach the ends to the bottom of the U, using water to adhere. Working in batches, use a slotted spoon to lower the pretzels into the boiling water. Cook, flipping once, until slightly puffed, 30 seconds per side. Transfer to an oiled baking sheet; brush with beaten egg and sprinkle with pretzel salt. Bake at 350 degrees F until golden brown, 20 to 25 minutes.