Preheat and prep: Heat the oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish. Cut tortillas into quarters.
Brown the turkey: Warm a large skillet over medium heat.
Add olive oil if your turkey is very lean. Cook ground turkey, breaking it up with a spoon, until no longer pink, about 5–7 minutes. Season lightly with salt and pepper.
Add aromatics: Stir in diced onion and cook until softened, 3–4 minutes.
Add garlic and cook 30–60 seconds until fragrant.
Season and simmer: Sprinkle in taco seasoning. Stir to coat. Add water or broth and simmer 1–2 minutes to thicken slightly.
Stir in the mixers: Add black beans, corn, and drained tomatoes with green chiles.
Cook 2 minutes to warm through. Taste and adjust salt, pepper, or seasoning as needed.
Layer the bake: Spread 1/3 cup salsa on the bottom of the baking dish. Add a layer of tortilla pieces to mostly cover the base.
Spoon half the turkey mixture over the tortillas. Sprinkle with 1/3 of the cheese.
Repeat: Add another layer of tortillas, the remaining turkey mixture, and another 1/3 of the cheese. Top with a final layer of tortillas, spread the remaining salsa over the top, and finish with the last 1/3 of the cheese.
Bake: Cover loosely with foil and bake 15 minutes.
Remove foil and bake another 8–12 minutes, until the cheese is melted, bubbly, and lightly golden around the edges.
Rest and garnish: Let it rest 5–10 minutes so it sets and slices cleanly. Top with chopped cilantro and any extras you like.
Serve: Scoop into squares and add sour cream or Greek yogurt, avocado, jalapeños, shredded lettuce, and a squeeze of lime.