Combine your active sourdough starter, oil, flour, salt and water in a KitchenAid mixer bowl. Use the dough hook to mix the dough, and knead for a solid 7-8 minutes. The dough is ready when it pulls away from the bowl and becomes quite stiff.
Transfer the dough to a well-oiled bowl, cover with plastic for 4 hours if not overnight.
After that time, dump the dough onto a lightly floured surface. Roll or flatten into a large rectangle and cut into 14-16 pieces.
Shape your bagels: pinch the ends over and meet at the bottom, shaping into a ball. Push your finger through the middle to form the "hole", and widen to about 1.5-2 inches. Repeat.
Place the shaped bagels on a greased cookie sheet or counter top. Cover with a damp towel, and allow to rise again for 30-45 minutes.
During that time, combine the 2 quarts water + baking soda in a one gallon stock pot. Bring to a low boil. Preheat your oven to 450 degrees F.
Place 3-4 bagels at a time into the baking soda + water mixture. Boil for 30 seconds on each side. Remove with a slotted spoon and place back on the greased cookie sheet/baking mat.
Brush the bagels with the egg + water mixture (optional, but gives a nice shine). Top with your choice of toppings.
Bake for 13-15 minutes at 450 degrees F, or until bagels are a beautiful golden brown. Allow to cool before enjoying.