Arrange a rack in the middle of the oven and heat the oven to 350℉.

Dice 1 medium yellow onion (about 1 cup). Core, seed, and dice 1 medium red bell pepper (about 1 ½ cups). Mince 2 garlic cloves. Drain and rinse 1 can black beans.

Heat 1 tablespoon of the olive oil in a large, high-sided skillet over medium-high heat until shimmering. Add 1 pound lean ground beef and cook, breaking up the meat with a wooden spoon, until browned and cooked through, 6 to 8 minutes. Using a slotted spoon, transfer the meat to a plate, then pour off any fat from the skillet.

Reduce the heat to medium. Add the remaining 1 tablespoon olive oil and heat until shimmering. Add the onion, bell pepper, and garlic, and cook, stirring occasionally, until softened, about 5 minutes. Return the beef and any accumulated juices to the skillet, add the black beans, and stir to combine. Add 1 tablespoon chili powder, 2 teaspoons ground cumin, 1 teaspoon dried oregano, 1 teaspoon kosher salt, and ¼ teaspoon black pepper, and stir to combine. Cook for 2 minutes.

Remove from skillet from the heat. Transfer ¼ cup tomato salsa from a 16-ounce jar into a 9x13-inch baking dish, then pour the remaining salsa into the skillet and stir to combine.

Assemble the lasagna: Spread the salsa out in the baking dish into a thin layer. Arrange 4 (8-inch) tortillas in a single layer on top of the salsa, overlapping them as needed. Dollop and spread ⅔ cup of the sour sour cream. Spoon half of the meat mixture over the sour cream and spread in an even layer. Sprinkle with 1 ⅓ cups of the shredded Mexican cheese blend.

Repeat layering the following: 4 tortillas, ⅔ cup sour cream, the remaining meat mixture, and 1 ⅓ cups shredded cheese. Top with the remaining 4 tortillas and remaining ⅔ cup sour cream. Sprinkle with the remaining 1 ⅓ cups cheese.

Bake uncovered until the cheese is melted and lightly browned, 30 minutes. Let cool for at least 15 minutes before serving. Garnish with the desired toppings.