Whisk together the flour, xanthan gum, and salt. Then add the starter, water, and olive oil. Mix using the dough hook of your standing mixer until evenly combined.
Mold the dough into a ball. Place it in a bowl lightly covered with olive oil and dusted with flour. Cover and leave it on the counter 8-10 hours (overnight).
Lightly kneed your dough and divide it into six sections. On a floured surface, shape each section into a ball by flattening the dough and then folding the two sides over to the middle, repeating on the other two sides. Flip the dough so the smooth side is face up. Poke your finger into the middle and wiggle it around to form the hole.
Boil each bagel for 1 minute in a pot of water containg the brown sugar and baking soda.
Place on a baking sheet with parchment paper and bake at 425 degrees for 30 minutes.
