Heat olive oil in a large pot over medium heat. Add the diced onion and sauté until soft and translucent, about 5 minutes. Stir in the garlic and cook for another 30 seconds until fragrant, being careful not to burn it.
Add the diced red bell pepper and cubed sweet potatoes to the pot. Stir to coat the vegetables in the oil and onions, and cook for 3 to 4 minutes to slightly soften them. This step helps develop flavor and prevents raw-tasting sweet potatoes in the finished chili.
Sprinkle in the cumin, smoked paprika, chili powder, cinnamon, and cayenne pepper. Stir well to evenly coat the vegetables in the spices. Cook for 1 to 2 minutes to allow the spices to bloom and release their aromas.
Pour in the black beans, diced tomatoes, and vegetable broth. Stir everything together and bring the mixture to a gentle boil. Once boiling, reduce the heat to low, cover, and simmer for 25 to 30 minutes. Stir occasionally to prevent sticking and allow the sweet potatoes to become tender.
Taste the chili and season with salt and pepper as needed. For a creamier texture, you can use an immersion blender to blend a portion of the chili, or mash some of the sweet potatoes directly in the pot. This adds a luscious, thick consistency without changing the flavors.
Serve the chili hot with your favorite toppings. Try avocado slices, fresh cilantro, lime wedges, or a sprinkle of vegan cheese. This chili is perfect on its own or alongside cornbread, brown rice, or a simple salad for a complete meal.