In a large bowl, mix all ingredients except baking soda together. If using additions (dried blueberries, olives, etc.), then add now.
Stir well to combine, then turn out onto a clean surface and knead for 4-5 minutes, until the dough is smooth and somewhat elastic. (Yes, the gluten-free dough will have some spring in its step.)
Roll the dough into a ball. Using a sharp knife, cut into 8 equal portions, like you would pie slices.
Roll each portion into a ball. Cover the balls with a damp kitchen towel and let rise for 20 minutes.
After letting them rise, shape the bagels. Now, most gluten-free bagel recipes that I researched (actually, most bagel recipes in general!) instruct one to poke one's finger through the centre. I find this rather barbarian. Instead, you're going to roll the dough into a ring. (See the video above for a demo.)
Place your dominant hand over one end of the dough. (It doesn't matter which end, although one may feel more comfortable than the other in the next step.)
With your other hand, flip the rope over the back of your dominant hand so that the two ends meet up under your dominant hand's palm.
Gently roll the two ends back-and-forth a few times under your palm to seal them. You may wish to roll them under 2-3 fingers, or to shape afterwards in order to make sure that the hole isn't too large.
Repeat for remaining bagels.
Place the bagels in a lightly floured surface and let rise, covered with a damp towel, for 20 minutes.
While the bagels are rising, bring a large pot of water to the boil and preheat your oven to 425ºF (220ºC).
At the boil, add your baking soda to the pot. This will help your bagels brown up in the oven. For browner bagels, add more baking soda.
Once the bagels are risen, boil them 1-2 at a time (or more, once you've gotten the hang of it). To do this, use a spatula or large slotted spoon to lower each bagel gently into the water. Boil for one minute, then flip and boil for another minute. Very gently remove to a cornmeal-dusted baking sheet.
If using a topping, dip the prettiest side of each bagel in the topping before placing topping-side-up on the baking sheet.
Bake for 20 minutes, or until the bagels are uniformly golden brown.
Let cool for a few minutes before cutting, spreading, and enjoying.