Preheat the oven to 375°F (190°C).

Spray a 9x13 inch baking dish with nonstick spray. Set it aside.

Lay 2 of the flour tortillas into the bottom of the 9x13 baking dish. Using a sharp knife or pizza cutter, trim the excess tortilla edges. Use the 2 trimmed tortillas as a pattern to trim the remaining 2 tortillas for the second layer of the lasagna.

Using a 3-4 quart saucepan over medium-high heat, add the ground beef, onion, and minced garlic. Cook the ground beef until it is cooked through and no longer pink. Reduce the heat to medium-low.

Using a small mixing bowl, whisk together the taco seasoning and 1 cup of water. Pour over the cooked ground beef. Cook for another 2-3 minutes, or until the meat mixture begins to thicken. Stir often. Remove from the heat.

Arrange 2 of the trimmed flour tortillas in the bottom of the prepared baking dish.

Evenly spread half of the meat mixture on top of the tortillas.

Evenly spread half of the salsa over the meat mixture.

Evenly sprinkle half of the black beans over the salsa.

Evenly sprinkle half of the shredded cheese over the beans.

Arrange the last 2 tortillas over the shredded cheese, and repeat the final layers of ingredients (meat, salsa, beans, and the remaining cheese).

Bake for 20-25 minutes. Remove from the oven, and garnish with chopped cilantro. Top with sour cream and pico de gallo if desired. Serve while hot.