Get a cast-iron or heavy-bottom pan very hot over high heat. Drizzle a little oil in the pan and reduce the heat to medium. Add the pork.
Stirring once or twice, heat the pork through, letting some of it get crispy, about 5 minutes. Transfer the meat to a serving dish and keep it in a warm oven.
Return the same pan to medium heat and, doing two tacos at a time, add 1/4 cup of the shredded cheese for each taco directly to the pan. Make two small piles of cheese in the pan.
When the cheese is melted, bubbly, and browning on the edges, lay one tortilla on each portion of melted cheese. Using a spatula, flip the tortillas to lightly toast the other side.
Repeat with as many tacos as you plan to serve.
With the tortillas cheese side up, pile on the pork and top with the chipotle pineapple salsa.