Heat the oil in a large dutch oven or stock pot over medium-high heat. Once the oil is glistening, add the onion, bell peppers, and sweet potatoes and cook, stirring, until the onion begins to soften, 5 minutes. Add the garlic and cook, stirring, until fragrant, about 2 minutes more.
Stir in the beans, tomatoes, enchilada sauce, chili powder, cumin, bay leaves, garlic powder, onion powder and salt until combined. Add enough water to cover the beans (1 to 2 cups).
Bring the mixture to a boil, then reduce the heat to low and simmer, stirring occasionally, for about 1 hour, or until the potatoes are tender and the chili has thickened.
Divide among bowls and serve topped with cilantro, green onions and avocado, if using. Store in the refrigerator for up to 1 week or in the freezer for up to 2 months.
