Preheat oven to 350 F. In large saucepan, place lentils, brown rice, and 5 cups of water. Bring to a boil, reduce heat, and simmer until both lentils and rice are tender, about 30 minutes. Drain well.

Meanwhile, in large skillet, heat grapeseed or olive oil over medium heat. Add onion and eggplant, and cook until softened, about 5 minutes. Add carrot and garlic; cook for 2 minutes. Place tomato paste, chipotle pepper, mustard powder, oregano, cumin, salt, and pepper in pan, and heat for 1 minute. Stir in crushed tomatoes and simmer for 10 minutes. Stir balsamic vinegar into sauce. Stir lentils and rice into mixture, and heat for 5 minutes.

On baking dish, place pepper halves cut sides up, and fill with rice and vegetable mixture. Cover with foil and bake for 30 minutes, then uncover and bake for another 15 to 20 minutes. Garnish with parsley.