Preheat the oven to 400 degrees. Line a baking sheet with foil. Wash the potatoes well, then dry with a paper towel. Coat each potato in vegetable oil, then prick the skin a few times with a fork. Place the potatoes on the baking sheet and transfer into the oven. Bake for 45 minute to an hour, or until soft all the way through.
While the potatoes are baking, prepare the toppings. Prepare the enchilada sauce according to this recipe, then set aside. Slice the green onions and jalapeño, shred the cheese, rinse and drain the black beans, and allow the corn to thaw.
Once the potatoes are cooked through, remove them from the oven (but leave it on, the potatoes will go back in). Cut each one lengthwise down the center, then once across. Open the potatoes up and mash the insides slightly.
Drizzle a couple tablespoons of enchilada sauce over each potato, then top with black beans, corn, jalapeños, and a handful of cheddar cheese. Transfer the potatoes back into the oven for 3-5 minutes, or until the cheese has melted. Remove the potatoes from the oven, drizzle with more sauce if desired, then sprinkle with sliced green onions.
*If you don't want to make homemade enchilada sauce, substitute with one cup of store bought enchilada or taco sauce.