mofongo
Mofongo is a popular food in Puerto Rico because it is the unofficial "king" of Puerto Rico. People enjoy the consistency of mashed plaintains, seasonings, and pork. You can find it in almost every restaurant in Puerto Rico.
Arroz con gandules
Arroz con gandules is considered Puerto Rico's national dish. A lot of people in Puerto Rico use it as a Christmas dish. That's probably why it is popular. It is a consistency of rice and pigeon peas.
flan
Popularity accounts for flan in Puerto Rico because of it's creamy, fluffy custard with a caramel top. It is a traditional dessert there. It can come in two flavors such as coco (coconut) and vanilla. You can find this in almost every restaurant's dessert menu in Puerto Rico.