First, add 22g of psyllium husk to a medium-sized bowl along with the 415g of warm water. Whisk the mixture until incorporated.
Add 15g of sugar to the psyllium mix. Set the bowl aside for a couple of minutes.
Add 360g of brown rice flour, 2 teaspoon baking powder, and 12g of salt to a large mixing bowl and whisk to incorporate. Then, once the psyllium gel starts to thicken, add both the psyllium mix and the sourdough starter to the bowl with the dry ingredients.
Mix the dough by hand or use an electric mixer with dough hooks. Continue mixing until all of the ingredients are evenly incorporated.
Shape the loaf & ferment
Wash your hands and turn the dough over onto a lightly floured working surface. Shape the dough into a ball and flatten it with your hands.
Then, fold each side of the dough onto itself. Take the top and fold it onto the center of the dough and repeat with the bottom and both sides. Then, flip the loaf onto the other side and shape it into a ball once again by turning the dough around and tucking it under itself.
If you want to add seeds to the top, turn the dough top side down onto a plate covered with sesame or linseeds, then transfer the loaf into a proofing basket.
If you don't have a proofing basket, you can use a mixing bowl lined with a kitchen towel. Make sure to flour the kitchen towel as well as the proofing basket to prevent sticking.
Cover the dough with a kitchen towel and let it ferment and proof for about 5 hours at room temperature or 12 to 18 hours in the refrigerator.
The dough should puff up and rise some but it won't double in size. The time of proofing will largely depend on the temperature in your house.
Bake
Once the dough is done proofing, gently turn it over onto a working surface and carefully tuck the sides of the loaf under itself by turning it in a circle with your hands. This will allow for a taller loaf.
Then, turn the bread onto a piece of parchment paper and score it. Scoring means cutting the surface of the dough with a razor or a sharp knife. You can either make one large cut or create a pattern!
Lower the parchment paper with the bread into the Dutch oven and cover it with the lid.
Place the bread into the cold oven and start preheating it to 450F/230C. Once the oven is preheated, start the timer and bake for 40 minutes.
Then, take the bread out of the Dutch oven and place it onto the oven rack. Turn the temperature down to 350F/175C and bake for another 30 minutes.
Cool
Take the bread out and let it sit on a cooling rack until no longer warm to the touch. Don't cut the bread too soon, or it will be gummier. Use a serrated knife to slice the bread. Enjoy!