Add the gluten-free oats to a high speed blender. Process until they resemble flour. It’s fine if there are a few larger pieces of oats in the oat flour.
Warm the soy milk to 110ºF/43ºC. Combine the psyllium husk with the soy milk in a small bowl or measuring cup. Mix well and set aside. It will begin to thicken and resemble runny oatmeal.
Combine the brown rice flour, oat flour, potato starch, tapioca starch, baking powder and salt in the bowl of a stand mixer fitted with the hook attachment. Stir together until well mixed. Then add the instant yeast and mix again.
Add the psyllium gel, maple syrup, olive oil and vinegar to the flour mixture. Stir on low speed until the dry ingredients are incorporated. You may need to scrape down the bowl a few times. Once all of the flour is incorporated, increase the speed to medium low and mix for 5 minutes.
Once the mixing time has elapsed, allow the dough to rest for 10 minutes in the bowl.
Turn the dough out onto a lightly floured surface. Knead the dough gently a few times until you can form it into a smooth circle. Pat the dough out into a rectangle shape as wide as your bread pan. Then roll the dough up into a log, tucking the ends under, and place it into a Pullman pan.
Cover the dough and leave it to rise in a warm place for about an hour or until it has doubled in size.
Place a pan of water on the bottom rack of your oven. Preheat the oven to 400ºF / 204ºC.
Once the dough has risen, place it in the preheated oven. Immediately reduce the temperature to 375ºF / 190ºC. Bake at 375ºF / 190ºC for 30 minutes with steam (do not open the door during this time). Remove the steam pan and bake for another 20-30 minutes at 375ºF / 190ºC. The final internal temperature should be at least 205ºF / 96ºC on an instant read thermometer.
Remove the loaf from the oven and allow it to cool completely before slicing; it will take 4 hours or more. Overnight cooling is best. If you slice it too soon, the inside will be gummy. If your bread feels too crisp on the outside, place it in a closed bread bag and the outside will soften.
Notes
To store: This bread is best right after it’s sliced, but it will stay fresh for 2-3 days at room temperature in an airtight container or plastic bag.To freeze: Once the bread has cooled, slice the loaf. Wrap it in two layers of plastic wrap, then place it inside a freezer bag. Freeze for up to 2 months. To thaw, remove the bread from the freezer and leave it on your kitchen counter until it’s no longer frozen.