Combine the 1 1/2 cups warm water, the sugar, and kosher salt in the bowl of a stand mixer and sprinkle the yeastSoft pretzels are always made with yeast dough and are very similar to bagels. on top. Set aside until the mixture foams, about 5 minutes.
Add the flour and butter and, using the dough hook attachment, mix on low speed until well combined. Change to medium speed and knead until the dough is smooth and pulls away from the side of the bowl, 4 to 5 minutes.
Remove the dough from the bowl, clean the bowl, then oil it well. Return the dough to the bowl, cover with plastic wrap, and set aside in a warm place until the dough has doubled in size, 50 to 55 minutes.
Heat oven to 450ºF. Line 2 half-sheet pans with parchment paper and lightly brush with oil, about 1 tablespoon per pan. Set aside.
Bring the remaining 10 cups water and the baking soda to a rolling boil in a Dutch oven.
Meanwhile, turn the dough out onto a lightly oiled work surface and divide into 8 equal pieces. Roll out each piece of dough into a 24-inch rope. Make a U-shape with the rope, and, holding the ends of the rope, cross them over each other and press onto the bottom of the U in order to form the shape of a pretzel. Place on a half-sheet pan. Repeat with the remaining pieces of dough.
One by one, place the pretzels in the boiling water for 30 seconds. Remove them from the water using a large flat spatula. Return them to the sheet pans, brush the top of each pretzel with the beaten egg yolk and water mixture, and sprinkle with pretzel salt.If you don’t have pretzel salt, coarse sea salt will do.
Bake until dark golden brown in color, 12 to 14 minutes. Transfer to a wire rack for at least 5 minutes before serving.