To a large bowl or to bowl in a stand mixer, mix together the sourdough discard, water, sugar, instant yeast, salt and flour.
Knead by hand about 5-8 minutes or knead in a stand mixer for about 5 minutes until it comes together and forms a smooth ball. Add a little more flour as needed. The dough will still be sticky, but not overly sticky. Pinch off a piece of dough and roll it into a ball in your fingers. If it forms a ball with minimal sticky residue left on your fingers, you can stop adding flour. Check out a few other tips for kneading dough here. Lightly oil a bowl or container (affiliate link) and turn the dough around in the bowl to cover it lightly with the oil. Drape a kitchen towel or some plastic wrap over the bowl and let dough rise for 1-1 ½ hours.
Line a baking sheet with parchment paper.
Once dough has doubled in size, flour a counter with 1-2 Tablespoons flour and punch down the dough. Turn it out onto the floured surface and separate into 4 sections.
Roll each section into a long strand and cut each strand into 6-8 pretzel pieces. Place each pretzel bite on the parchment paper.
Heat ½ cup of water in the microwave until almost boiling. Add 1 Tablespoon of baking soda (it will bubble up a little) and mix together. Make sure the baking soda is completely dissolved before proceeding.
Using a pastry brush, brush each pretzel bite with the baking soda/water mixture.
Preheat the oven to 500 degrees. Let the pretzel bites rise for about 10-15 minutes (usually the amount of time it takes for the oven to preheat) before baking.
Bake the pretzel bites for about 8 minutes until crisp and lightly brown on the outside.
While the pretzel bites are baking, melt the unsalted butter and prepare any toppings (salt, parmesan cheese, cinnamon sugar).
As soon as the pretzel bites are baked through, remove them from the oven and brush with melted butter. Continue adding butter until all of the butter is on the pretzel bites. It may seem like a lot of butter, but keep adding it for the best taste and flavor.
Top with salt, cinnamon sugar or parmesan cheese and enjoy immediately.