01 - Whisk together gluten-free flour, sugar, yeast, and salt in a large mixing bowl until thoroughly combined.
02 - Pour warm water, vegetable oil, and apple cider vinegar into dry ingredients. Mix vigorously until a sticky, uniform dough forms.
03 - Gently fold blueberries into the dough using a spatula, taking care not to crush or burst the berries.
04 - Shape dough into a smooth ball, cover bowl with a clean towel, and let rise in a warm area for 45 minutes until slightly puffy.
05 - Preheat oven to 425°F and line a baking sheet with parchment paper.
06 - Divide dough into 8 equal portions on a lightly floured surface. Roll each into a ball, poke a hole through the center, and stretch gently to form bagel rings. Place on prepared baking sheet.
07 - Bring 2 quarts water to a gentle boil in a large pot. Stir in honey or maple syrup if using.
08 - Carefully lower 2-3 bagels at a time into boiling water. Cook for 30 seconds per side, then remove with a slotted spoon and return to baking sheet.
09 - Brush each bagel with beaten egg and sprinkle generously with coarse sugar.
10 - Bake for 20-22 minutes until deeply golden brown. Transfer to wire rack and cool completely before slicing.