Heat oil in a large saucepan over medium-high heat. Add onion and sauté until it caramelizes, about 20 minutes. Add garlic and continue to sauté for 30 seconds. Add chili powder, cumin, oregano, and cayenne pepper, and cook for 30 seconds. Add water, lentils, and tomatoes. Increase the heat, and bring the stew to a boil. Reduce the heat to low and simmer until lentils are tender, about 30 minutes. Stir in green onions. Add salt, and taste for seasonings. Serve hot and enjoy!
Notes
You can use the store-bought chili powder here, but the homemade one tastes so much better & is really easy to make!