Which ingredient is NOT found in a cubano sandwich?

A cubano sandwich is a traditional Cuban sandwich that typically consists of layers of pork, ham, Swiss cheese, pickles, and mustard, all piled between Cuban bread and pressed until warm and crispy. The essential characteristics of a cubano include the combination of meats—specifically roasted or slow-cooked pork and ham—along with the distinct addition of Swiss cheese, which melts beautifully when the sandwich is pressed.

When analyzing the ingredients, it is clear that pork, Swiss cheese, and ham are integral components of a cubano sandwich. In contrast, egg is not a traditional ingredient in this sandwich. While certain variations may include additional ingredients or toppings, the classic cubano remains adherent to its original formulation, which does not feature egg. Therefore, identifying egg as not belonging in a cubano sandwich reflects an understanding of the traditional recipe that defines this popular dish.