In the bowl of a heavy-duty mixer, add the flours, xanthan gum, salt, and flax, if using. Blend on low just enough to mix well.
In a small bowl, stir together the honey and warm water, and then add the yeast.
When the mixture becomes foamy, blend into the dry ingredients.
Add the olive oil, eggs, and vinegar. Beat on medium-high to high speed for 3 minutes.
Turn the mixture into a greased, 9×5 loaf pan, and spread evenly. The dough will be sticky. Brush or spray the top lightly with olive oil.
Cover the dough and let the dough rise in a warm place until doubled in bulk, 20 to 25 minutes. I wait until the dough has reached or slightly exceeded the top of the loaf pan.
Preheat oven to 400 degrees. Bake for 40 to 45 minutes or until a cake tester poked into the center comes out clean. After approximately 30 minutes, drape lightly with a piece of aluminum foil to prevent over-browning.
Remove from pan and to a wire rack to cool. Once cooled, wrap the loaf in plastic or place in a zipper top bag and store in the refrigerator. The bread will last for over a week.