Dissolve yeast in 1 1/2 cups lukewarm water in a small bowl. Let stand until bubbly, about 5 minutes.
Mix 2 cups whole wheat flour, sorghum flour, and salt in a large plastic container with a lid. Stir in yeast mixture with a wooden spoon, adding more water if dough is not evenly moistened. Cover with a lid and let rise in a warm, draft-free place until doubled in volume, about 2 hours.
Dust a cutting board with 1 tablespoon whole wheat flour. Turn the dough out onto the board and briefly knead with your hands. Shape into a round loaf. Sprinkle remaining 1 tablespoon flour over a clean dish towel; place in a bowl. Place dough in the bowl and cover with the ends of the dish towel; let rise until nearly doubled in volume, about 1 1/2 hours.
Preheat oven to 450 degrees F (230 degrees C) after dough has been rising for 45 minutes. Place a lidded Dutch oven inside after 25 minutes.
Remove hot Dutch oven from the oven using oven mitts. Place dough inside carefully, using floured hands. Cover with the hot lid.
Bake bread covered in the preheated oven for 30 minutes. Remove the lid and continue baking until top is golden brown, about 10 minutes. Lift bread out of the Dutch oven using oven mitts and tap the bottom; if it sounds hollow, bread is done. Let cool for at least 1 hour on a wire rack.