Preheat the oven to 425°F (220°C). Line a sheet pan with foil.
Place the potatoes on the prepared pan; bake at 425°F for 45 to 60 minutes or until very tender. You will know they are done when you can slightly squeeze them and they give a little. The baking time will vary depending on the size.
Add the bell pepper to a small sheet pan lined with parchment paper, and season with ¼ teaspoon of the salt and ⅛ teaspoon of the pepper. Set aside.
Add the beans, cumin, ½ teaspoon salt, and remaining ¼ teaspoon pepper to a small pot, and stir well. Set aside. Add the corn to a separate small pot. Set aside.
Once the potatoes are done baking, cool them for 10 minutes. Then slice them in half lengthwise. Use a spoon to scoop out the flesh of the potatoes, leaving about ¼ inch remaining along the edges and bottom. Flip the potato shells over and lightly spray the skin sides with nonstick spray and season with the remaining ¼ teaspoon salt or more to taste. If you avoid oil, you can skip the spray, but I found it to make them extra crispy and flavorful.
Increase the oven temperature to 450°F (230°C). Line the same pan with parchment paper, and place the cut potatoes cut sides down. Bake at 450°F for about 10 minutes or until the skins are very crispy. If you didn’t use oil, they take a few minutes longer to get crispy. At the same time, place the pan of bell peppers on the bottom rack below the potatoes. Both the potatoes and bell peppers should be done at about the same time. The bell peppers should be beginning to char along the edges.
When the potatoes and bell peppers have just a couple of minutes left, heat up the beans and corn.
Fill each potato with beans, corn, and bell peppers and stir the mixture around a bit. Top with chopped jalapeños.
Peel and mash the avocado in a bowl, and add the lime juice. Mash repeatedly until completely smooth. Add to a ziplock bag, cut off a tiny corner, and drizzle on top of each potato. Season the tops with an extra sprinkling of salt and black pepper, if desired.