In the bowl of stand mixer, add dough ingredients in the order in which they're listed. Using the dough hook, start mixer on low until dough comes together. Turn speed up to medium and mix for 5 minutes.
Remove bowl from mixer and cover bowl. Refrigerate for at least 3-4 hours, or up to 4 days.
Preheat oven to 400°F. Line two baking sheets with silicone mats (preferable to parchment as pretzels tend to stick to parchment paper).
Knead dough on a lightly floured surface. Divide into 6 equal. Roll one piece at a time into a rope about 26-28 inches long. Shape into a "U" shape on the counter. Twist ends twice and fold down onto bottom. Press ends firmly into bottom portion of pretzels so they will stick. Repeat with remaining pretzels. For pretzel nuggets (bites), roll into long rope shape and cut into 1-2 inch pieces.
Pour hot water into shallow bowl (I use a pie pan) and add baking soda to water. Whisk until the baking soda dissolves completely. Dip each pretzel and nugget into the baking soda solution, using a spoon to splash the tops of each pretzel (which prevents you from having to turn over the pretzel while in the solution). Carefully remove and blot on a paper towel before placing onto prepared baking sheets.
While still slightly wet, sprinkle each pretzel/nugget with Maldon flake salt, coarse sea salt or kosher salt, or pretzel salt.
Bake for 15-17 minutes, or until golden brown and puffed dramatically. While pretzels are baking, fill a shallow bowl or pie pan with melted butter and set aside.
Remove from the oven and immediately dip each pretzel (both sides) in melted butter while still hot. Serve warm or at room temperature.
Notes
Pretzels are best served warm from the oven, but can be kept at room temperature for 3-4 days in an airtight container. To refresh them, place in a 450 degree F oven for 5 minutes.  To make without psyllium husks, simply reduce the water amount in the recipe to 60 milliliters. The dough may be a little harder to work with (but not impossible), so I would suggest refrigerating it overnight for better results. Â