In a large bowl or Ziplock freezer bag, combine all the ingredients for the marinade. Place the meat inside the marinade and refrigerate for a minimum of 1 hour and up to 8 hours.
Place the meat into grill pan and cook for 3-4 minutes per side. Remove the meat from the pan and place onto a clean cutting board. Let the meat rest for 5 minutes to seal in all the juices.
Heat oil in a large skillet over medium-high heat. Then, add sliced onions and jalapeños. Cook for 4-5 minutes, until the onions and jalapeños are caramelized.
In a large skillet, add butter. Heat until melted. Place tortilla into the pan. Then, add a layer of cheese on half of the tortilla. Add slices of carne asada, onions and jalapeños, a second layer of cheese and a few spoonfuls of pico de gallo.
Cook for 2-3 minutes until the cheese begins to melt. Then, fold the tortilla in half and flip and cook for 2-3 minutes until the cheese is melted and the tortilla is golden brown.