Feed starter. 8 hours before you’re ready to make these bagels, feed your sourdough starter by adding 30 grams of sourdough, 45 grams of flour, and 45 grams of water. (This will give you 100 g of active sourdough if you want more to feed later, double this.) Stir to combine, cover, and let it sit at room temperature for 8 hours or until it’s doubled in size.
Make the dough. Add the warm water and active sourdough starter to a large mixing bowl. Stir until the water and sourdough starter are almost fully incorporated. Drizzle the honey in and stir. Add the salt and the flour. Using a wooden spoon, stir to combine as much as you can. You may need to use your hands to add the rest of the flour.
Rest. Place the formed dough in a clean bowl and cover with a towel, plate, or plastic wrap. Let it sit covered for 1 hour.
Stretch and folds. After 1 hour, remove the cover. Wet your hands with some water (this will prevent the dough from sticking to your hands). Pick up one side of the dough, then stretch it up and fold the dough over onto itself. Continue this process 3 or 4 times, turning the dough so the bottom is facing up. Cover and sit for 30 minutes. This strengthens the dough, and you will notice the dough becoming more soft and pliable with each stretch and fold session. Repeat the stretch and folds 3 more times for a total of 4 stretch and fold sessions. Rise. Cover and let the dough sit at room temperature for 12 hours (or overnight).
Divide and rest. Remove the cover and place the dough on a clean, dry surface. Divide the dough into 12 equal portions and form them into a ball. The dough may be a little sticky. If that's the case, add some flour to your workspace. Cover and let it sit for 1 hour. Prep baking soda bath. Prepare the water bath by adding the water, honey, and baking soda (if using) to a large pot. Bring to a boil over medium-high heat. Baking soda gives the bagels a golden brown color. Prep for baking. While the water is coming to a boil, cut a piece of parchment paper into twelve 4x4-inch (2.5x2.5 cm) squares. Set aside. Line 2 baking sheets with a piece of parchment paper then set aside. Preheat the oven to 375℉ (190 ℃).
Shape. Uncover the dough balls and shape them into bagel shapes by pressing a hole into the middle of the dough and then stretching the hole. Place the prepared bagel onto one of the parchment squares. Repeat this process 11 more times until all of the dough balls have been shaped into bagel shapes. The parchment paper allows for easy transfer, preventing the dough from sticking to your hands or the counter. Cook in the water bath. Working in batches (3 fit perfectly into the pot) place the bagels into the water bath. Cook for 3 minutes, flipping them halfway through (about 90 seconds). Transfer the boiled bagels to the lined baking sheet. If you are adding toppings, top them as soon as the bagels have been removed from the water bath.
Bake. Bake at 375℉ (190℃) for 25 minutes or until golden brown. Remove from the oven and cool for 5 minutes, then move them to a cooling rack. Cool on the cooling rack for 10 minutes before cutting into them.