In a small bowl, combine the warm water, active dry yeast, and granulated sugar. Stir gently and let sit for 5 to 10 minutes until the mixture is foamy.
In a large mixing bowl, whisk together the gluten free all-purpose flour blend, brown rice flour, tapioca starch, xanthan gum (if using), and salt.
In a separate bowl, beat the eggs, then add the vegetable oil and apple cider vinegar. Mix until combined.
Add the wet ingredients to the dry ingredients, then pour in the yeast mixture once it is foamy.
Using a stand mixer fitted with a paddle attachment or a hand mixer, mix on medium speed for 3 to 5 minutes until the dough is smooth and slightly sticky. The dough will be more like a thick batter than traditional bread dough.
Grease a 9×5 inch loaf pan with oil or non-stick spray. Transfer the dough into the pan and smooth the top with a wet spatula.
Cover the loaf pan loosely with a clean kitchen towel or plastic wrap and let the dough rise in a warm place for 45 minutes to 1 hour, or until the dough has risen about 1 inch above the rim of the pan.
Preheat the oven to 375°F (190°C).
Bake the bread for 40 to 45 minutes until the crust is golden brown and a toothpick inserted into the center comes out clean.
Remove the bread from the oven and let it cool in the pan for 10 minutes.
Transfer the bread to a wire rack and let it cool completely before slicing.