Pierce the potatoes with a fork, rub with oil, and sprinkle with salt. Bake for 45-50 minutes, until tender.
Meanwhile, mix the tomatoes, black beans, and seasonings in a medium bowl.
When the potatoes are done, slice in half lengthwise. Scoop out most of the potato and add to the bowl with the bean mixture. Mix and divide between the potato shells. Top with cheese and return to the oven. Bake for 10-15 minutes, or until cheese is melted. Top with the scallions and serve.