In a large skillet, heat over medium heat and add 1 pound of lean ground beef. Cook for about 6-8 minutes until browned and no longer pink. Drain excess grease.

Stir in 2 tablespoons of tomato paste and 1 tablespoon of taco seasoning. Pour in 1/4 cup beef broth and let simmer for about 3 minutes until thickened.

Fold in 3 cups of shredded cheese until melted into the meat mixture.

Spoon half of the beef and cheese mixture onto one side of a large tortilla. Fold the tortilla over to create a half-moon shape and press edges to seal.

Heat 1 tablespoon of vegetable oil in the skillet over medium heat. Toast the folded quesadilla for about 3-4 minutes on each side until golden brown and crispy.

Let the quesadilla rest for a minute, then cut into wedges and sprinkle with cilantro. Serve with sour cream or guacamole.