Gluten-Free Sourdough Bread

Name: Gluten-Free Sourdough Bread
Prep time: 10 min
Cook time: 35 min
Total time: 45 min
Cuisine: American
Ingredients: 3/4 cup gluten-free sourdough starter ((click for recipe)); 2 cups sparkling water (or water); 1 egg; 2 tablespoons olive oil; 1 tablespoon maple syrup (or honey); 2 teaspoons apple cider vinegar (or vinegar); 1½ cups gluten-free all purpose flour (with xanthan gum) (plus extra for coating); 1 cup tapioca flour; 1 cup brown rice flour; 1/2 cup millet flour; 1 tablespoon psyllium husk powder; 1 teaspoon sea salt or pink salt; 1/4 teaspoon baking soda