1. Activate Your Sourdough Starter: The day before you plan to mix your dough, feed your sourdough starter. It should be active, bubbly, and pass the float test (a small spoonful floats in water) before you begin. This ensures it has enough strength to leaven your bagels.

2. Mix the Dough Ingredients: In a large mixing bowl, combine your active sourdough starter, warm water, and barley malt syrup (or honey). Stir until the starter is mostly dissolved. Then, add the bread flour and salt. Mix with a sturdy spoon or your hands until a shaggy dough forms and no dry flour remains.

3. Initial Kneading and Rest: Turn the dough out onto a lightly floured surface. Knead for about 5-7 minutes until the dough starts to become smoother and more elastic. It will still be a bit sticky. Form it into a ball, place it back in the bowl, cover it with a damp cloth or plastic wrap, and let it rest for 30 minutes. This rest allows the flour to fully hydrate.

4. Develop Gluten with Stretch and Folds: Over the next 2-3 hours, perform a series of “stretch and folds” every 30-45 minutes. To do this, gently stretch a portion of the dough up from the bowl and fold it over itself. Rotate the bowl and repeat 3-4 times. This builds gluten strength without intensive kneading. The dough will become noticeably smoother and more elastic with each set.

5. Bulk Fermentation: After the stretch and folds, cover the bowl and let the dough bulk ferment at room temperature (around 70-75 F) for 4-6 hours, or until it has increased in volume by about 30-50% and feels airy. The exact time will depend on your starter’s activity and room temperature.

6. Shape the Bagels: Gently turn the dough out onto a lightly floured surface. Divide it into 8-12 equal pieces (depending on desired bagel size). Roll each piece into a smooth ball. Then, using your thumb, poke a hole through the center of each ball and gently stretch the hole to about 1.5-2 inches in diameter. Place the shaped bagels on a parchment-lined baking sheet.

7. Cold Proofing: Cover the baking sheet loosely with plastic wrap and refrigerate the bagels for 8-16 hours. This cold proofing develops flavor and makes the bagels easier to handle. They should feel slightly puffy but not overly risen.

8. Boil and Bake: Preheat your oven to 450 F (230 C) with a baking stone or inverted baking sheet inside. Bring a large pot of water to a rolling boil and add 1 tablespoon of baking soda. Gently drop 2-3 bagels into the boiling water (don’t overcrowd). Boil for 30-60 seconds per side. Remove with a slotted spoon, drain well, and place them back on the parchment-lined baking sheet. If desired, sprinkle with toppings immediately. Bake for 18-22 minutes, or until golden brown and cooked through.