2 1/2 tsp yeast
1 Tbsp sugar
1 1/2 cups water
3 cups flour
1/2 cup buckwheat flour
1/2 cup wheat bran
2 Tbsp flaxseed
1 1/4 tsp salt
3/4 tsp balsamic vinegar
Oil for bowl
Pour water into a large microwave-safe bowl and heat to 120° (test it with your pinkie - it should be hot, but not so hot that you can't keep your finger in it). Stir in the sugar, then add yeast. Let sit a few minutes until foamy.
Add 2 1/2 cups of the flour, buckwheat flour, wheat bran, flaxseed, salt and vinegar to the yeast mixture and mix well with a sturdy spatula or wooden spoon. Add the last 1 cup of flour and stir in as much as possible. Turn out onto lightly floured surface and knead for 5 minutes. The dough will be smooth and elastic, not sticking to your hands, but maybe to the counter still a bit.
Oil the bowl and place the dough in it, rolling it in the oil. Cover lightly with plastic wrap and let rise until doubles in size, about an hour.
Punch down the dough and shape into a ball or loaf, depending on your pan. Place in pan then quickly cut two or three slashes on the the top with a sharp knife. Cover again lightly with plastic wrap. Let rise one hour.
Heat oven to 375°. Bake for 40 minutes, or until the crust is golden brown and the internal temperature is 200°.