Dough. In a mixing bowl, mix together all of the dough ingredients except for the egg. Knead for 5-10 minutes until the dough is smooth and elastic.
Shape the dough into a ball and place it into a lightly greased bowl. Cover with plastic wrap and allow to rest at room temperature for 2 hours.
Portion the dough into six equal portions, preferably by weight. Roll each one out to about 20 inches, allowing the strands to rest for a few minutes if they pull back. Shape each strand into a pretzel shape and place onto a piece of parchment paper. Cover loosely with plastic wrap or a tea towel and allow to rest for 30 minutes.
Preheat oven to 450° F. Beat the egg in a small bowl.
Boil. Bring a large pot of water to a boil and add the baking soda. Boil the pretzels for approximately 30 seconds, just until they float. If the pretzels seem stuck to the bottom, use tongs or a long wooden spoon to release them. Do not over-boil the pretzels.
Drain and transfer the pretzels to a parchment lined baking sheet. Egg wash each one and bake for 10-12 minutes. The tops should be golden brown and the internal temperature should be at least 190° F.
Cinnamon Sugar Coating. While the pretzels are baking, mix the cinnamon sugar together and melt the butter over the lowest possible heat.
Once the pretzels come out of the oven, brush both sides of a pretzel with the melted butter. Using tongs, dip the pretzel in the cinnamon sugar mixture. Allow to cool on a wire rack. Repeat with the remaining pretzels.