Preheat the oven to 400°F (200°C). Spread the cubed sweet potatoes on a baking sheet, drizzle with olive oil, and toss to coat. Roast for about 25 minutes, or until tender and slightly caramelized, stirring halfway through.
While the sweet potatoes roast, heat a large pot over medium heat. Add a splash of olive oil and sauté the diced onion until translucent and fragrant, about 5 minutes.
Add the minced garlic, smoked paprika, cumin, and chili powder to the onions. Cook for another 30 seconds until the spices become aromatic.
Pour in the diced tomatoes with their juices and vegetable broth. Bring the mixture to a gentle simmer, mixing well to combine all flavors.
Once the roasted sweet potatoes are ready, add them to the pot. Stir gently to incorporate with the broth and spices.
Add the drained black beans and season with salt and pepper to taste. Cover the pot and let the chili simmer on low heat for about 10 minutes, allowing flavors to meld.
Uncover the pot and taste the chili, adjusting salt and pepper if needed. The sweet potatoes should be tender, and the chili thickened but still saucy.
Serve the hot sweet potato chili in bowls, garnished with fresh herbs or a squeeze of lime if desired. Enjoy the hearty, smoky flavors with your favorite bread or on its own.