3 cups plus 2 tablespoons (438 g) all purpose gluten free flour (I used Better Batter)
2 1/4 teaspoons xanthan gum (omit if your blend already contains it)
25 grams Expandex modified tapioca starch
3 tablespoons (38 g) whole grain teff
1/2 cup + 1 tablespoon (68 g) certified gluten free oat flour
1/4 teaspoon cream of tartar
1/4 teaspoon baking soda
2 tablespoons (25 g) granulated sugar
1 tablespoon (9 g) instant yeast
2 teaspoons kosher salt
4 tablespoons (56 g) unsalted butter, at room temperature
1 teaspoon apple cider vinegar
1 tablespoon (21 g) unsulphured molasses
2 egg whites (50 g), at room temperature
1 1/2 cups (12 fluid ounces) warm milk, about 95°F
Molasses bath, for boiling (about 1 tablespoon unsulphured molasses, dissolved in 6 to 8 cups water)
Egg wash (1 egg + 1 tablespoon lukewarm water, beaten)
In the bowl of your stand mixer fitted with the paddle attachment, place the flour, xanthan gum, Expandex, teff, oat flour, cream of tartar, baking soda, sugar and yeast. Whisk with a separate handheld whisk to combine well. Add the salt and whisk again to combine. Add the butter, vinegar, molasses, egg whites and milk, and mix on low speed with the paddle attachment until the dough starts to come together. Switch out the paddle attachment for the dough hook, and knead the dough on medium speed for about 5 minutes. The dough should be smooth and stiff, and only slightly tacky to the touch.
Transfer the dough to a large piece of lightly floured unbleached parchment paper. With a bench scraper, divide the dough into 8 equal parts. Take the first piece of dough, and roll it back and forth on the parchment paper into a cylinder about 6 inches long and 1 inch in diameter. Coil the dough into the shape of a bagel, with one end overlapping the other by about 1 inch. Press down a bit on the ends to seal. Place on a parchment lined baking sheet and set aside. Repeat with the remaining pieces of dough. Spray the bagels lightly with warm water, cover the baking sheet with plastic wrap and place in a warm, draft-free area to rise until the dough is about 150% of its beginning volume (about 40 minutes). While the dough is rising, preheat your oven to 375°F. In the last 15 minutes of rising, place the 2 tablespoons sugar dissolved in 6 to 8 cups water in a medium-sized pot. Place the pot on the stove and bring to a rolling boil over medium-high heat.
Once the dough has risen, remove the plastic wrap. Carefully place the bagels, 2 at a time, in the boiling sugar water. Allow to boil about 90 seconds, then gently turn over in the water and boil for another 90 seconds. Remove the bagels to the parchment-lined baking sheet. Repeat with the remaining bagels. Brush the tops of the bagels generously with the 1 beaten egg.
Place the baking sheet in the center of the preheated oven and bake for about 30 minutes, rotating once during baking, or until the bagels are a deep golden brown and sound hollow when tapped. Remove the bagels from the oven, and allow to cool on the baking sheet for 10 minutes. Transfer to a wire rack to cool completely before serving.