1. Preheat oven to 350°F.
2. In a small sauce pot, add millet and water. Bring to boil, reduce to simmer and cover. Cook for 15 minutes. After 15 minutes, turn heat off and let millet sit about 5 minutes, then fluff with fork.
3. In a frying pan, heat oil over medium-low heat. Add onion and saute 10 minutes, until translucent.
4. Add zucchini to onions and saute another 8-10 minutes until onions are golden and zucchini is soft. Add garlic and saute another minute. Remove from heat.
5. In a large mixing bowl, place 1 cup cooked millet, the onion and zucchini mixture, 1 cup black beans, 1 cup diced tomato and all the seasonings. Mix until incorporated.
6. Lay peppers in a baking dish and place 1/4 of mixture in each pepper half.
7. Top each pepper with 1 tablespoon tomatoes.
8. Cover dish with tin foil or lid and bake 30 minutes. After 30 minutes, turn heat to 400°F, remove lid or foil and bake another 10 minutes uncovered.