1. Combine the Dough Ingredients: In a large mixing bowl, combine the sourdough discard, 2 1/2 cups all-purpose flour, salt, and granulated sugar. Gradually add the warm water, mixing with a wooden spoon or your hands until a shaggy dough forms.

2. Knead the Dough: Turn the dough out onto a lightly floured surface. Knead for 8-10 minutes until the dough is smooth and elastic. It should spring back slowly when poked. If the dough is too sticky, add a tiny bit more flour, but be careful not to add too much.

3. First Rise (Bulk Fermentation): Place the kneaded dough in a lightly oiled bowl, turning once to coat. Cover the bowl with plastic wrap or a damp kitchen towel and let it rest in a warm place for 1-2 hours, or until it has visibly increased in size and looks bubbly. For a deeper flavor, you can refrigerate the dough overnight (8-12 hours).

4. Shape the Bagels: Gently punch down the dough and divide it into 8 equal pieces. Roll each piece into a smooth ball. Using your thumb, press a hole through the center of each ball and gently stretch the hole to about 1-1.5 inches in diameter. Place the shaped bagels on a parchment-lined baking sheet.

5. Prepare for Boiling and Baking: Preheat your oven to 425 F (220 C). Bring a large pot of water to a rolling boil and add the baking soda. This alkaline bath is crucial for the bagel’s signature chewy crust.

6. Boil the Bagels: Carefully drop 2-3 bagels into the boiling water at a time, making sure not to overcrowd the pot. Boil for 30 seconds to 1 minute per side. Use a slotted spoon to remove the bagels and place them back on the parchment-lined baking sheet. If desired, sprinkle with your chosen toppings immediately after boiling.

7. Bake the Bagels: Transfer the baking sheet to the preheated oven. Bake for 20-25 minutes, or until the bagels are golden brown and sound hollow when tapped on the bottom.

8. Cool and Serve: Allow the bagels to cool on a wire rack for at least 15-20 minutes before slicing and serving. This allows the interior to set properly, ensuring the best texture.