Add the warm water, yeast and sugar to the bowl of a stand mixer. Let sit for 5 minutes or until bubbly. If the yeast isn't bubbly, it isn't active and the pretzels will not work. Repeat this step with new yeast until it is bubbly.
Add the melted butter, salt and flour to the stand mixer. Turn on LOW and allow the stand mixer to knead the dough for 10 minutes.
The dough should be very soft, but shouldn't stick to the sides of the bowl at all.
Allow the dough to rise until double. (1 hour on the counter) If using the Instant Pot, spray the liner with non stick spray and then let the dough rise in the Instant Pot on the Yogurt NORMAL setting for 15 minutes.
After the dough has doubled, punch down the dough and divide into 8 equal sized pieces. Set aside.
Combine the water and baking soda in either a large pot on the stovetop or in the Instant Pot. Bring the soda water to a boil. If using the Instant Pot, set it to Saute HIGH.
Preheat oven to 425°.
While the soda water is coming to a boil, shape the pretzels.
Take one piece of dough and roll into a 2 ft long rope. Lay the rope in the shape of a 'U'.
Cross the ends of the 'U'. Repeat this step so the rope is twisted.
Fold the ends of the 'U' down towards the bottom of the 'U' and pinch the ends to create the pretzel shape. (see image diagram in post).
Repeat with the remaining dough.
Once all of the pretzels have been shaped, gently place each pretzel (one by one) in the boiling soda water. Allow the pretzel to boil for about 30 seconds before removing and transferring to a parchment paper lined cookie sheet.
Repeat with remaining pretzels.
Brush each pretzel with egg white (if desired) and sprinkle with sea salt.
Bake at 425° for 10 minutes.
Allow to cool for 5 minutes before eating.
Best eaten within the hour. If you'd like to store for a longer period of time, I suggest freezing the pretzels as soon as they are cool. Reheat the pretzels in the oven at 425° for 8-10 minutes.