In a large pot, heat the olive oil over medium heat. Add the chopped onion and bell pepper, sautéing until softened, about 5 minutes.
Stir in the minced garlic and cook for another minute until fragrant.
Add the diced sweet potatoes to the pot, mixing well with the onion and pepper.
Pour in the vegetable broth, diced tomatoes (with their juices), black beans, chili powder, cumin, smoked paprika, cayenne pepper, salt, and pepper. Stir to combine everything.
Bring the mixture to a simmer and cover the pot. Cook for about 25-30 minutes, stirring occasionally, or until the sweet potatoes are tender.
Once the sweet potatoes are soft, taste the chili, adjusting the seasoning with more salt, pepper, or spices as desired.
Serve hot, garnished with fresh chopped cilantro and avocado slices on top.
Notes
Adjust the spices according to your heat preference.