Heat olive oil in a large pot over medium heat.
Add chopped onion and bell pepper to the pot, sautéing until soft.
Stir in minced garlic and cook for about 1 minute until fragrant.
Add diced sweet potatoes, chili powder, cumin, and smoked paprika; stir well.
Pour in the diced tomatoes with their juice and vegetable broth; bring to a simmer.
Add black beans, stirring to combine; season with salt and pepper.
Simmer the chili for 20–30 minutes, stirring occasionally until sweet potatoes are tender.
Taste and adjust seasoning if necessary before serving.
Serve hot, garnished with avocado, cilantro, and lime wedges if desired.