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, roll and cut the dough into small 'bites' by rolling the dough into a long rope and then cutting it into one inch sections. Repeat with all of the dough.
Once all of the pretzels cut, gently place each pretzel 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. (This parchment paper will probably get really wet, so you'll want to eventually transfer the pretzels to another sheet of parchment paper prior to baking.)
Repeat with remaining pretzels.
Brush each pretzel with egg white 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.