In a large pot or Dutch oven, heat olive oil over medium heat. Add the diced onions and cook until they’re soft and starting to brown, about 5 to 6 minutes. Add minced garlic and cook for an additional minute.
Sprinkle in chili powder, cumin, oregano, and optional garlic and onion powders. Stir for about a minute until fragrant. Add diced sweet potato, black beans, diced tomatoes, tomato paste, green chilies, and vegetable broth. Mix well.
Bring the mixture to a boil, then reduce heat and cover with the lid slightly askew. Simmer for about 30 to 40 minutes, stirring occasionally, until sweet potatoes are tender. Add more water if too thick.
Serve hot in bowls topped with garnishes like diced avocado, cilantro, or tortilla strips.