Cut the top 1/4 off the bell peppers and remove the seeds and membranes, place bell peppers in a large baking dish and set aside. Dice and reserve the extra flesh from the tops, discarding the stem.
Heat a large saute pan over medium high heat. Brown the ground beef, then remove from pan. Drain excess fat from pan.
Add 1 tablespoon olive oil to the pan and heat over medium heat. Add the onions and the diced parts of the bell peppers, season with salt and pepper. Sauté for 10-15 minutes, until soft and golden.
Add the tomato paste and garlic, stir together until mixed and becoming fragrant, 1-2 minutes.
Add the corn and black beans, stir to combine. Add the meat back to the pan along with the taco seasoning. Cook for 1-2 minutes, stirring until fully combined.
Remove from heat and stir in 3/4 cups of the cheese, stir until cheese is mixed in and melted. Taste and season with more salt if needed.
Fill bell peppers with meat mixture and bake for 30 minutes.
After 30 minutes, remove from oven and top peppers with the remaining 1 cup cheese, return to the oven for 15-20 minutes, or until peppers are cooked and cheese is browning and bubbly.
If you use a packaged Taco Seasoning, go easy on the salt in the rest of the dish. Taste at the end and add more salt only if needed.Depending on the size of your peppers you may have some extra filling. If you have small bell peppers you may have enough filling for 8, if they are large it will be enough for 6.If you don't want to use Pepper Jack, you can use Cheddar.