Mix yeast, sea salt, sugar, and warm water in a small bowl, whisking until sugar dissolves. Let stand until foamy, about 5 to 10 minutes (about 8 minutes is right).
Place flour into a large bowl. Using two butter knives, a pastry cutter, or your fingertips, cut the butter into the flour until the mixture resembles coarse crumbs.
Slowly pour yeast mixture over flour mixture, stirring with a wooden spoon or your hands to combine. Using your hands, gather dough together. Turn dough onto a lightly floured surface, and knead until it is no longer sticky, about 5 minutes.
Lightly brush a large bowl with oil and turn the dough to coat. Cover with plastic, and let rise in a warm place, until the dough has doubled in size. About 1 hour. (If you want, you can place the bowl of dough in the refrigerator over night).
Cut dough into 12 equal pieces, and roll each into an 18-inch rope. Form a U shape with 1 rope, and twist ends together twice. Fold twisted portions backward along center of U shape to form a circle, then gently press ends of rope onto dough to seal. Transfer to an oiled baking sheet, and repeat. Let rise for 20 minutes.
Preheat oven to 475ºF.
Bring a large pot of water to a boil, and add baking soda and 1 1/2 tablespoons granulated sugar. Boil pretzels in batches until puffed and slightly shiny, 1 to 2 minutes per side. Transfer to wire racks to drain.Place pretzels on an oiled baking sheet. Mix the 1 teaspoon water and egg in a small bowl. Brush each pretzel with the egg wash. Sprinkle the with the pretzel salt or course grain sea salt.
Bake until golden brown and cooked through, about 15 minutes. Pretzels will keep, uncovered at room temperature for up to 12 hours.
Re-warm in a 250 degree oven if desired, or toast the pretzels in a toaster, and serve with mustard. Enjoy!