Give the boneless short ribs a sprinkling of salt on both sides.
For the marinade, add the listed ingredients to a blender and combine well.
Create a single layer of the meat in a casserole dish. Cover with the marinade and be sure to get some underneath as well. Cover with plastic and marinate in the fridge for an hour or so.
For the Pico de Gallo (optional), start by giving the tomatoes, jalapeno, and cilantro a good rinse. Peel the onion and de-stem the tomatoes and jalapenos. I usually twist off and discard the bottom, thicker portions of the cilantro stems, but keep the upper portion of the stems that hold the leaves together.
Finely chop the tomatoes, onion, and jalapeno into 1/4" sized chunks. Finely dice the cilantro. For a milder version you can start by using only 1 of the jalapenos and adding more incrementally if you want more heat. Combine everything in a mixing bowl along with 1/2 teaspoon of salt and the juice of two limes. Mix together well and taste for seasoning. Add additional salt and lime if necessary (I added more salt to this batch).
Preheat a grill or cast iron pan. I used cast iron at just over medium heat and added a glug of oil to it. Once the pan is piping hot, pat dry the meat and cook each piece for 2-3 minutes per side or to your desired temp. Medium rare will be 130-135F but I cooked this batch towards well done to crisp up the edges.
Let the cooked meat rest for a few minutes before slicing. I usually cover it in some foil. Cut against the grain into thin strips. I cut these strips even further into bite-sized pieces.
To make a quesadilla, warm up a tortilla in a large, dry skillet over medium heat. Add the chopped Carne Asada, some Pico de Gallo (but not too much liquid), and plenty of cheese to only half of the tortilla. Fold onto itself and cook each side until crispy and golden brown. Cut in half and serve immediately.