Wash your pepper(s). For me, I make a serving as ½ a pepper, so I cut the peppers in half horizontally (leaving a top piece and a bottom piece). If you'd prefer to make a serving as 1 whole pepper, then cut the stem end off.
Carefully remove the ribs and seeds from the peppers. Sprinkle the inside of the peppers with salt and place them cut-side down into a baking dish. Cook for 20 minutes at 400° F.
While peppers cook, stir together leftover taco ingredients and corn. Taste mixture and season with salt and pepper or additional taco seasonings as needed.
When the peppers are done cooking, take them out of the oven and turn the cut-side up in the pan. Stuff them with the prepared mix. Cover with foil and put back into the oven for 20 more minutes.
When the peppers are done cooking, remove foil and let cool for 5 minutes. Set each pepper on a plate and sprinkle with cilantro, avocado, and a squeeze of lime juice. If you made the serving size a ½ pepper, remember that there is still a stem attached to one of the servings, which will need to be cut out and discarded.