Prepare your leaven 4-12 hours prior to mixing your dough. Preparing a leaven just means feeding your starter.
In the bowl of a stand mixer, combine water and leaven. Stir in sugar and salt.
Add the flour one cup at a time and bring it together with your hands or dough whisk. You will have a dry, stiff dough.
Place the dough hook attachment on the mixer and mix on low speed for 5 minutes.
Cover the bowl with plastic wrap and let it rest and ferment at room temperature overnight.
The next morning, remove your dough and place it on a clean work surface. Divide the dough into 8 equal pieces. This can be done with a kitchen scale or you can eye-ball it.
Roll each piece into a ball and then poke your index finger or thumb into the dough to make a hole. Spin the dough around your finger to shape and widen the hole and place bagels on a baking sheet lined with parchment paper. Cover with a towel and leave to rise for 30-60 minutes.
Preheat the oven to 425°F and prepare your boiling water.
Boil bagels for 2 minutes on each side and remove with a slotted spoon. Place bagels on a wire rack and allow them time to drip before placing them back onto the parchment lined sheet pan.
Dip bagels into the preferred topping.
Place bagels into a preheated oven for 20 minutes or until the tops are golden brown and the internal temperature reads 200°F on a quick read thermometer.