Cut bell peppers in half vertically and carefully core them to remove the seeds. Set aside.
Slice chorizo into 1/4" pieces and set aside.
Prepare the seasoning: combine chili powder, paprika, cumin, ground red cayenne pepper, onion powder, garlic powder, black pepper, and salt in a small bowl.
Next, prepare the filling. Heat vegetable oil in a large skillet over medium-high heat until shimmering, then add minced garlic and sauté until fragrant, about 1 minute.
Add chorizo and cook for 5 minutes, turning over occasionally with a spatula.
Turn heat to medium and add corn, black beans, jalapeno, onion, and seasoning. Stir to combine and cook for 6-7 minutes, stirring occasionally, until heated through and beans are slightly softened.
While the filling is cooking, grill both sides of each pepper over medium-high heat until lightly charred.*
Transfer peppers to a foil-lined baking dish. Stuff peppers with filling, then top each pepper with a sprinkle of shredded cheese.
Broil on low for 5 minutes.
Serve hot with slices of avocado.