Preheat the oven to 375°F.

Lay 2 of the flour tortillas into the bottom of a 9x13 baking dish. Use a knife to trim excess edges and use the trimmed pieces as patterns for the remaining tortillas.

Spray a 9x13 baking dish with nonstick spray; set aside.

In a large saucepan over medium-high heat, cook ground beef, onion, and garlic until beef is browned and cooked through. Drain excess fat.

In a small bowl, whisk together taco seasoning and water. Add to meat mixture and cook for 2-3 minutes until thickened, stirring frequently.

Arrange 2 of the tortillas in the bottom of the prepared dish.

Spread half of the cooked meat mixture over the tortillas.

Spread half of the salsa over the meat.

Sprinkle half of the black beans and cheese over the salsa.

Repeat layers with remaining tortillas, meat mixture, salsa, beans, and cheese.

Bake uncovered for 20-25 minutes. Garnish with cilantro, and serve with sour cream and pico de gallo if desired.