Preheat the oven to 425°F/220°C.
Combine the baking soda with very hot (almost boiling) water in a shallow bowl (the water should be deep enough to dip the dough ropes in it) and stir until dissolved.
Punch the dough to deflate, place on a surface (do NOT use flour), and divide into 6 equal pieces. Roll each one into a thin long (30inch) rope. → Hold the ends and slap the middle onto your counter to make them even longer and thinner. If the dough seems tight, let it rest for a few minutes and continue with the other pieces.
Dip each rope into the soda bath for a few seconds, transfer on a with parchment paper-lined baking sheet, and form into a pretzel shape (see blog post for step-by-step instruction with pictures). Sprinkle with coarse sea salt, poppy seeds, or sesame seeds.
Bake the pretzels for 8 minutes until golden.
Meanwhile, melt the remaining 2 tbsp vegan butter. As soon as the pretzels are coming out of the oven, transfer them on a cooling rack, and brush them with the melted butter.