1. Combine the Wet Ingredients and Starter: In a large mixing bowl, combine your sourdough starter discard, warm water, sugar (or honey), and salt. Whisk everything together until the sugar and salt are dissolved and the mixture is well combined. It should look milky and slightly bubbly.

2. Mix in the Flour to Form the Dough: Gradually add the all-purpose flour, about a cup at a time, mixing with a wooden spoon or your hands until a shaggy dough forms. Once all the flour is incorporated, turn the dough out onto a lightly floured surface.

3. Knead the Dough Until Smooth: Knead the dough for about 8-10 minutes. At first, it will be sticky, but as you knead, it will become smoother, more elastic, and less sticky. You’re looking for a dough that springs back slowly when poked.

4. First Rise (Bulk Fermentation): Place the kneaded dough into a lightly oiled bowl, turning it once to coat. Cover the bowl with plastic wrap or a damp kitchen towel and let it rest at room temperature for 2-3 hours. The dough should become slightly puffy, but it won’t double in size like yeast dough.

5. Shape the Bagels and Overnight Proof: Gently punch down the dough and divide it into 8-10 equal pieces. Roll each piece into a smooth ball. To form the bagel hole, poke a hole in the center of each ball with your thumb and gently stretch it to about 1-inch in diameter. Place the shaped bagels on a parchment-lined baking sheet, cover loosely with plastic wrap, and refrigerate overnight (8-12 hours). This slow, cold proof develops flavor and makes them easier to handle.

6. Preheat Oven and Prepare Boiling Water: The next morning, preheat your oven to 425 F (220 C) with a rack in the middle. Bring a large pot of water to a rolling boil and add the baking soda. This creates an alkaline bath that helps with the crust development.

7. Boil and Top the Bagels: Carefully drop 2-3 bagels into the boiling water (don’t overcrowd the pot). Boil for 30-60 seconds per side. Using a slotted spoon, remove the bagels and place them back on the parchment-lined baking sheet. If desired, sprinkle with your chosen toppings immediately after boiling.

8. Bake Until Golden Brown: Transfer the baking sheet to the preheated oven and bake for 20-25 minutes, or until the bagels are deep golden brown and sound hollow when tapped on the bottom. Let them cool on a wire rack before slicing and serving.