In a deep and large skillet, add enough oil so that it’s at least ¾-inch deep; heat over medium heat. Once the oil is hot, about 3 to 4 minutes later, add a few quesadillas at a time to the hot oil, making sure not to crowd the skillet. Cook for 2 to 4 minutes per side, or until golden brown and crisp. Transfer, with a slotted spoon, to a paper towel-lined platter to drain. Serve hot, with the salsa of your choice.