Preheat the oven to 450°F.
In a 12-inch oven-safe skillet, heat 1 tablespoon olive oil over medium-high heat.
Add 1/2 onion (chopped), 1/2 poblano pepper (seeds removed and chopped), 1 red bell pepper (seeds removed and chopped), and 1 small zucchini (chopped). Sauté 4–5 minutes, until the vegetables are tender.
Stir in 2 cloves garlic (minced) and cook 1 minute more.
Add 1 cup fresh or frozen corn, 15 oz black beans (canned, rinsed and drained), 1 tablespoon chili powder, 1 teaspoon ground cumin, 1/2 teaspoon smoked paprika, 1 teaspoon kosher salt, 1/4 teaspoon black pepper, and the juice of 1/2 lime. Stir to combine.
Pour in half of the 20 oz red enchilada sauce and stir.
Add 8 corn tortillas (cut into thick strips) and stir so the strips begin to absorb the sauce.
Pour in the remaining enchilada sauce and stir until all the tortilla strips are coated. Cook 2–3 minutes, stirring occasionally, until the sauce thickens slightly.
Stir in 1 cup shredded cheddar or Mexican blend cheese until melted and incorporated.
Sprinkle the remaining 1 cup shredded cheese evenly over the top.
Transfer the skillet to the preheated oven and bake 5 minutes, or until the top cheese is melted. Use oven mitts when handling the hot skillet.
Remove the skillet from the oven and let the enchiladas rest for 5 minutes.
Top with sliced green onion, 1/4 cup chopped cilantro, 1 avocado (pit removed and chopped), and radish slices. Scoop onto plates and serve warm.