Prepare your 9- × 5-inch loaf pan by coating it with cooking spray.
In a small bowl, combine the sugar and warm water.
Sprinkle the yeast on top, stir gently, and set aside for 5-10 minutes until it becomes foamy.
In a large bowl, whisk together the brown rice flour, sunflower seeds, flaxseed meal, potato starch, soy flour, tapioca flour, xanthan gum, and salt.
Make sure all the dry are thoroughly combined.
In a separate medium bowl, whisk together the eggs, egg whites, warm soymilk, olive oil, molasses, and apple cider vinegar until smooth.
Pour the dry into the wet ingredient mixture.
Using an electric mixer on low speed, beat for 1 minute until just combined.
Add the foamy yeast mixture, increase the mixer speed to medium-high, and beat for 3 minutes. The batter will be thick and sticky.
Pour the batter into your prepared loaf pan and smooth the top.
Cover the pan loosely and let it rise in a warm, draft-free place for 1 hour, or until it has risen noticeably.
Towards the end of the rising time, preheat your oven to 350°F (175°C).
Bake the loaf for 45 to 55 minutes. The crust will be a deep golden brown and look very dark, but this is normal. The internal temperature should read 205-210°F (96-99°C).
Let the bread cool in the pan for 10 minutes before carefully turning it out onto a wire rack to cool completely before slicing.
Don't slice it warm! Gluten-free bread needs to cool completely to set its structure. Slicing into a hot loaf can result in a gummy, dense texture.
