The traditonal recipe for this time-honored Mexican dish was known as al pastor due to the marinated pork, which is usually grilled on a vertical rotisserie. The marinade is normally prepared with achiote, a variety of spices as well as ground red chilies. One day, when I went by this street vendor stand which offers these, I realized that they were using pineapple cooked together with the cheese and thought, wow, that seems tasty and sure enough it was. This is my take on their tacos. I love it and I am sure you will as well.