Preheat your oven to 350°F (175°C). Rinse the bell peppers, slice them in half lengthwise, and remove the seeds. Place them cut-side up on a baking sheet lined with parchment paper. Bake for 20 minutes to soften.
While the peppers are baking, heat a medium skillet over medium heat. Add the ground beef and cook until browned, breaking it up as it cooks. Drain the grease once it's fully cooked.
Turn the heat to low. Add the taco seasoning, salsa, black beans, and corn to the skillet. Stir well and let it simmer for 5 to 7 minutes until everything is heated through and combined.
Take the peppers out of the oven and fill each one with the taco mixture. You can slightly overfill them—it’s okay if they’re nice and full!
Return the stuffed peppers to the oven and bake for another 7 minutes.
Remove from the oven and sprinkle the tops with shredded cheddar cheese. If you like, add a dollop of sour cream and a few slices of avocado before serving.