Preheat and prep: Warm a large nonstick skillet over medium heat. Dice the onion, bell pepper, and zucchini.
Rinse the beans and corn if using.
Brown the protein: Add the ground turkey or chicken to the dry skillet. Cook, breaking it up with a spatula, until no longer pink, about 5–7 minutes. Season with a pinch of salt and pepper.
Sweat the aromatics: Add the onion and bell pepper.
Cook 3–4 minutes until softened. Stir in the garlic and zucchini, and cook 1–2 minutes until fragrant.
Spice it up: Sprinkle in taco seasoning, cumin, and smoked paprika. Stir to coat the meat and vegetables so the spices bloom in the heat.
Add the body: Stir in diced tomatoes, tomato paste, and 2–3 tablespoons of water or broth.
Mix well to create a saucy base that clings to the meat.
Fold in the extras: Add corn and black beans if using. Reduce heat to medium-low and simmer 3–5 minutes to let flavors meld. Adjust salt and pepper.
Cheesy finish: Sprinkle the shredded cheese over the top.
Cover the skillet for 1–2 minutes to melt.
Garnish and serve: Top with chopped cilantro or green onions. Serve with lime wedges and any light toppings you like.