Preheat oven to 450 degrees. Scrub the skin of the sweet potatoes with water and dry off. Pierce potatoes with a fork all over the outside. Place a rack onto a baking sheet. Set sweet potatoes on the rack. Place baking sheet in preheat oven to bake for 30 minutes. Remove from oven and brush potatoes with canola oil. Sprinkle with salt. bake for another 15-20 minutes or until the centers are fully cooked.
While the potatoes bake, cook the beans. Set a medium sauce pan over medium heat. Add olive oil and minced garlic. Cook just until it starts to brown. Add can of beans with juices. Add cumin and salt. Cook until the mixture simmers and some of the juices have thickened, about 8 minutes.
Once the sweet potatoes are done, transfer them to the serving platter. Split them down the middle and push the ends towards the center to create a well in the center of the potato. Lightly salt the center of the potato.
Spoon out about ⅓ cup of beans (without the juices) and place into each potato. Mix diced onion and chopped cilantro together in a small bowl. Distribute the onion mixture over the top of the beans. Finish off the potatoes with a squeeze of lime juice.