Make the pretzels: In a medium bowl, stir the flours, yeast, brown sugar, and salt together in a large bowl, then add the warm water until a shaggy dough forms.
Transfer the dough to a lightly floured surface and knead for 5 minutes until a smooth dough forms.
In a large clean bowl, grease with oil or with cooking spray. Place the dough ball in the bowl and cover with a spritzed or greased piece of plastic wrap. Let rise until doubled in size, usually an hour, but depends on how warm your home is. You can also use the a Proof setting on your oven, if you have it.
Line 2 baking sheets with parchment paper.
Transfer the dough to a clean, unfloured surface and divide dough in half. Then divide each half in half and continue until you have 24 even pieces of dough. Roll each piece into a rope about 9 inches long and 1/2 inch wide (the thinner the better). Line up the ropes on the baking sheets and cover loosely with clean cotton kitchen towel. Let rise for another 30 minutes.
Poach and bake: Preheat the oven to 325˚F and prepare the poaching liquid. In a large wide saucepan or Dutch oven over medium heat, bring 8 cups water to a simmer over medium heat. Add the baked soda and brown sugar and stir until dissolved. The water should foam slightly.
Gently drop your dough ropes into the simmering water, just a couple at a time. Poach for 15 seconds and with tongs, gently remove the ropes and return them to the baking sheets. Brush with egg wash and generously sprinkle with sea salt.
Bake for 50-60 minutes, checking every 20 minutes as they will begin to brown quickly. Bake until they're dark brown, glossy, and fully hardened. Transfer to a wire rack and let cool completely. Store the pretzels at room temperature in an airtight container for up to a week.