1. Activate the Yeast and Combine Wet Ingredients: In a large mixing bowl, combine the warm water, granulated sugar, and active dry yeast. Stir gently and let it sit for 5-10 minutes until the mixture becomes foamy, indicating the yeast is active. Once foamy, stir in the sourdough discard and melted unsalted butter until well combined.

2. Form the Dough: Gradually add the all-purpose flour and fine sea salt to the wet ingredients. Mix with a wooden spoon or your hands until a shaggy dough forms. Turn the dough out onto a lightly floured surface and knead for 5-7 minutes until it becomes smooth and elastic. It should feel soft and slightly tacky, but not sticky.

3. First Rise (Proofing): Lightly grease a clean bowl with a little oil. Place the dough in the bowl, turning it once to coat the top. Cover the bowl with plastic wrap or a clean kitchen towel and let it rise in a warm place for 60-90 minutes, or until it has roughly doubled in size. The dough should feel puffy and soft when gently poked.

4. Shape the Buns: Once risen, gently punch down the dough to release the air. Divide the dough into 8-10 equal pieces. Roll each piece into a smooth ball. For a more traditional pretzel bun shape, you can slightly flatten the ball into a disc. Place the shaped buns on a parchment-lined baking sheet, leaving some space between them.

5. Prepare the Baking Soda Bath: Preheat your oven to 400 F (200 C). In a large pot, bring 8 cups of water to a rolling boil. Carefully add the 1/2 cup of baking soda to the boiling water. Be cautious as the mixture will foam up significantly.

6. The Pretzel Bath: Using a slotted spoon or spatula, carefully lower one bun at a time into the boiling baking soda bath. Boil each bun for 30 seconds per side. The buns will puff up slightly and take on a slightly darker hue. Remove the buns from the bath, allowing excess water to drip off, and return them to the parchment-lined baking sheet.

7. Score and Season: Once all buns have been bathed, use a sharp knife or a clean razor blade to make a shallow “X” or a few parallel slits on the top of each bun. This helps them expand beautifully in the oven. Immediately sprinkle generously with coarse sea salt.

8. Bake to Perfection: Transfer the baking sheet to the preheated oven and bake for 15-18 minutes, or until the pretzel buns are deeply golden brown and sound hollow when tapped on the bottom. Remove from the oven and let cool slightly on a wire rack before serving.