Combine water, sugar, and salt in the bowl of a stand mixer fitted with dough hook. Sprinkle yeast on top and allow to sit 5 minutes.
Add flour and butter. Mix on low speed until combined. Increase to medium speed and knead until the dough is smooth and pulls away from the side of bowl, approximately 5 minutes.
Place dough in well-greased bowl, cover with plastic wrap, and sit in warm place for 50-60 minutes until the dough has doubled in size.
Line 2 baking sheets with parchment paper and spray with nonstick spray. Preheat Air Fryer at 400 degrees F.
In large stock pot or roasting pan, combine 10 cups of water and the baking soda and bring to a boil.
Place pretzel dough onto an oiled work surface and divide into 12 equal pieces. Roll each piece of dough into an 18-inch rope. Twist into pretzel shape (see notes in blog post).
One-by-one, place each pretzel into the boiling water for 30 seconds. Remove from water and place on parchment-lined baking sheet.
Brush the top of each pretzel with the beaten egg yolk and water mixture and sprinkle with pretzel salt. Place 3-4 pretzels directly into Air Fryer basket and cook 6 minutes at 400 degrees F. Turn soft pretzels over and cook another 6 minutes until dark golden brown.