A quesadilla is nothing more than a corn or wheat quesadilla that has been filled with cheese, folded over, and then heated up, until the cheese melts. The quesadilla originated in central and southern colonial Mexico, where people smothered their corn tortillas with Oaxaca cheese before grilling them on a flat griddle, called a comal.
In a Mexican setting, a quesadilla is generally served alongside green or red salsa, Mexican sour cream, guacamole, and chopped onions. A variety of ingredients are used with the cheese to fill the quesadilla. These include: chorizo, mushrooms, squash, flor de calabaza, and chicken. Guacamole is occasionally spread over the outside of the quesadilla for even more flavor.
In the United States, creative chefs have introduced a number of other fillings to the quesadilla. In recent years, healthy options like spinach, tofu, zucchini, and goat cheese have been added to quesadillas. Smoked salmon is another ingredient sometimes integrated into the quesadilla. When the fish is used, chefs usually pair it with pepperjack cheese, cream cheese, or goat cheese. Instead of traditional red salsas, smoked salmon quesadillas call for chipotle cilantro or avocado salsas.