Preheat the oven to 350°F (175°C).
In a large skillet over medium heat, cook the ground beef or turkey until browned. Drain excess fat if necessary.
Add the diced onion and minced garlic to the skillet, cooking until the onion is translucent, about 3-4 minutes.
Stir in the taco seasoning, black beans, corn, and salsa. Cook for an additional 5 minutes, allowing the flavors to meld.
In a 9x13-inch baking dish, spread a thin layer of the meat mixture on the bottom. Place a layer of lasagna noodles over the meat mixture.
Spread half of the remaining meat mixture over the noodles, followed by half of the sour cream and a layer of cheese.
Repeat the layering process with another layer of noodles, the remaining meat mixture, sour cream, and top with the remaining cheese.
Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.
Let the lasagna cool for 10 minutes before slicing. Top with shredded lettuce, diced tomato, black olives, and cilantro if desired.