Mix together starter, oil, sugar and water in the bowl of a stand mixer.
Add in flour and mix on low until a smooth dough forms. If adding inclusions, add up to 1/2 cup now. See notes below.
Knead in the stand mixer for 3-4 minutes.
Lightly oil the top of the dough and cover with plastic wrap.
Put the dough in the fridge for 12-18 hours.
Pull the dough out of the fridge and let it warm up on the counter for about an hour.
Shape dough into 16 equal sized pieces.
Preheat oven to 425 degrees.
Boil water in a large pot on the stove. Once the water is boiling, add 2 tablespoons of baking soda.
Using a slotted spoon, boil bagels for 20 seconds on each side working in batches of 2-3 at a time.
Place boiled bagels on a parchment lined baking sheet.
If adding toppings, brush each bagel with egg wash and sprinkle on toppings.
Bake at 425 for 25-28 minutes. Let the bagels cool COMPLETELY before cutting open. The bagels continue to bake on the inside until completely cooled.
Store leftovers in an air tight container or in the freezer for up to 3 months.