Add flour and salt and mix with a dough hook on medium-low speed for 6-7 minutes, until smooth and elastic.
Oil a large bowl and transfer the dough into it. Spray plastic wrap with cooking spray and cover the bowl with the sprayed side facing the dough. Let rise until doubled in size, about 40-60 minutes.
Preheat oven to 425.
When dough has doubled in size, cut into 12 equal portions. Form your dough into balls, keeping the seam at the bottom of the rolls.
Let rest for 10 minutes. While the dough is resting place a large pot or dutch oven on the stove and bring the water and baking soda to a boil. After the dough is done resting boil the dough balls in batches of 3-4 at a time, boiling for 1 minute on each side. Use a slotted spoon to remove them and place them on a parchment lined baking sheet.
Brush with melted butter and sprinkle with coarse salt. Use a very sharp knife or razor blade to score the tops of the buns.
Bake for 10 minutes then rotate the pan and bake for 6-8 more minutes, until browned. Allow to cool before serving.