This bread could be served to your gluten-free family every day of the week. It is made with hearty buckwheat and sorghum flours and uses no gums. The psyllium husks used as a binder allow the dough to be kneaded and shaped much like wheat bread. Mix the dough the night before and have fresh bread the next day.
Whisk together the water, brown rice sourdough starter, melted butter, honey, and eggs until everything is well-combined. Mix in the flax seed and the psyllium seed husk and allow to sit for 2 to 3 minutes to set up.
Add the flours and sea salt and mix well with a wooden spoon for several minutes. The dough should be sticky and wet, and therefore hard to mix, but will hydrate more through the souring process. Cover dough with a plate or damp towel and allow to sour for 8 to 18 hours, or overnight.
When ready to bake, prepare a baking sheet by buttering or applying parchment paper.
Divide dough in two and sprinkle a work surface with tapioca flour. Place one ball of dough on work surface and knead for several minutes, adding an additional 1/4 to 1/2 cup of flour as needed to keep dough from sticking. Despite this, the dough will still be very soft.
Once dough holds together in one cohesive ball, mold it into a round and place it on one half of the baking sheet. Repeat with other half. Cut three parallel slashes into tops of dough with a sharp knife. Allow to rise in a warm place for 2 to 4 hours.
Preheat oven to 400°F. Place baking pan in middle rack of oven and bake 25 to 30 minutes or until an internal temperature of 190°F is reached. You can use a thermometer to check this.
Move immediately to a cooling rack and allow to cool for at least 45 minutes before slicing.