Rinse quinoa well. If you forget to rinse the quinoa (as I did once), it will not taste very good. Bring water and quinoa to a boil, then reduce to a simmer. Cook until the water is absorbed, about 10-15 minutes. Set aside.
Slice the tops off the green peppers and take out the membranes and seeds. In a large pot, bring water to a boil and add green peppers. Cook until just tender. Set aside.
Sauté onion until soft.
Add chopped green pepper and garlic and cook until green pepper is tender.
Add half of each of the tomato sauce, cumin, oregano, and salt and pepper. Add all of the black beans. Cook for several minutes.
Add quinoa until mixed thoroughly.
Stuff each pepper with the mixture and put in a casserole dish.
On stove, heat the other half of the tomato sauce, cumin, oregano, and salt and pepper.
Pour the tomato sauce mixture on the bottom of the casserole dish.
Bake @ 350° for 35 minutes, or until peppers are tender.
Serve with sauce on the side or drizzled over the top.