Prep the chicken: If using raw chicken, pat dry and cut into bite-size pieces. Season with 1 teaspoon chili powder, 1 teaspoon cumin, 1/2 teaspoon smoked paprika, 1/2 teaspoon salt, and a few grinds of black pepper.
Sear the chicken: Heat 1 tablespoon oil in a large skillet over medium-high. Add chicken in a single layer and cook 4–6 minutes, stirring once or twice, until just cooked through.
Transfer to a plate.
Sauté the veggies: Add a little more oil if needed. Cook onion and bell pepper over medium heat for 3–4 minutes until softened. Stir in garlic and cook 30 seconds until fragrant.
Build the skillet: Add black beans, corn, diced green chiles (if using), and the cooked chicken back to the pan.
Pour in 1.5–2 cups enchilada sauce, stirring to coat. Taste and adjust salt, pepper, and spices.
Add tortillas (optional): Stir in tortilla strips and simmer 2–3 minutes to soften. If skipping tortillas, simmer to thicken slightly.
Cheese it up: Reduce heat to low.
Sprinkle cheese evenly over the top. Cover and cook 2–3 minutes until melted and bubbly around the edges.
Finish and serve: Remove from heat. Top with Greek yogurt or a dollop of sour cream, chopped cilantro, and green onions.
Serve with lime wedges. Add avocado if you like.