Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
Poke the sweet potatoes a few times with a fork and place on the prepared baking sheet. Bake for 45 minutes or until tender.
Meanwhile, heat oil in a medium skillet over medium heat. Add onion and garlic and cook for 3 minutes or until softened.
Add the cumin, chili powder, smoked paprika and black pepper. Stir to combine and cook for 1 minute.
Add the beans and tomatoes and stir to combine. Cook for 5 minutes or until heated through.
When the sweet potatoes are done baking, cut each in half lengthwise. Scoop out some of the flesh from each potato half into a bowl, leaving enough potato around the edges so that they keep their shape.
Add the bean mixture to the bowl with the scooped out potato flesh and mash together until combined.
Divide the mixture among the 8 potato halves. Place them back on the baking sheet and bake for an additional 10 minutes or until heated through.