Feed your starter: The night before you want to make your bagels, feed your sourdough starter so it’s active and bubbly in the morning.
Mix the Dough: In the morning, to a stand mixer, combine the active sourdough starter, water, honey, salt, and flour. Mix on low. The dough will be stiff—this is normal! Knead until the dough is smooth and pliable (about 10 minutes.)
Fermentation: Place the dough in an oiled bowl and cover with a damp tea towel or plastic wrap. Let it ferment at room temperature for 6–10 hours or until doubled in size.
Cold Fermentation: Once the dough has doubled, cover your bowl with plastic wrap and place it in the fridge to cold ferment overnight, for 10-12 hours. (this step is optional, but it makes for the best flavor and texture.)
Shape the Bagels: The next morning, turn the dough onto a floured surface. Divide the dough into 12 equal pieces. Roll each piece into a ball, flatten slightly, and poke a hole in the center with your finger. Gently stretch the hole to form a bagel shape. Cover the shaped bagels with a tea towel and let them rise in a warm spot for 1–4 hours, until puffy.
Boil the Bagels: Preheat your oven to 425°F. Bring a large pot of water to a boil and add the baking soda and honey or molasses. Using a slotted spoon, boil the bagels 2–4 at a time for 1 minute on each side.
Bake: If desired, dip the boiled bagels in your favorite toppings. Place them on a parchment-lined baking sheet and bake for 20–25 minutes, or until golden brown on top.
Cool: Let the bagels cool on a wire rack before slicing. Store them in an airtight container and enjoy within the first few days. To freeze them, preslice the bagels and freeze in a ziplock baggie for up to a few months.