Use a meat tenderizer to further tenderize the cube steak. Place the individual steaks between to sheet of parchment paper and pound each out to 1/2-inch thickness.
Put the tenderized steaks into a shallow dish and pour the white wine vinegar over them. Flip the steaks to ensure the vinegar coats each one completely.Allow the meat to sit in the vinegar for 20 minutes.
While the steaks are soaking, in a small mixing bowl, combine the adobo, granulated onion powder, granulated garlic powder, dried oregano, meat tenderizer, and black pepper. Generously sprinkle this spice rub on both sides of the meat. Marinate the meat for another 20 minutes to allow the seasoning to penetrate the meat.
While the Meat is Marinating, Prepare the Mayo-Kechu (or do this a week ahead)
In a separate mixing bowl, use a whisk to stir together the mayonnaise, ketchup, mustard, and adobo (and hot sauce if you're using it). Store this spread, covered, in the fridge until you're ready to assemble the tripletas.
Cook and Warm the Meats and Rolls
Heat a well-seasoned cast-iron griddle to medium-high heat. Once a drop of water dances on the surface of the griddle, press your seasoned meat onto the hot metal so that their entire surface makes contact with the griddle.
Sear the meat for 3 minutes per side for medium to medium-rare steak. If you plan to cook the meat to medium-well or well-done, decrease the griddle's temperature after the first side is seared. Cook it for 6 minutes on the second side.Transfer the steaks to a platter and tent a piece of foil over the dish to keep the steaks warm and allow them to rest for 10 minutes.
Decrease the heat of the griddle to low.Cut the pan sobao rolls in half to open them up, then place the bread on the uncleaned griddle cut side down. Allow the bread to soak up the juice and fat from the steak and take on color and flavor. Heat the pan sobao on both sides for 1-2 minutes, or until lightly toasted. Remove the rolls from the griddle and set them aside.
Use a carving or slicing knife to thinly cut the cube steak against the grain. Cutting across the ridges in the meat and not along them.Once the cube steak is sliced, return it to the warm griddle along with the pernil and ham slices. Top the ham with a slice (or two) of cheese towards the end of the warming period, which should only take about 3 minutes.
Assemble the Tripletas
While the meats are warming on the griddle, slather the mayo-kechu spread generously on one (or both) halves of the pan sobao. Top one half of the roll with the meats. Begin with the pernil, followed by a slice or two of cheese, a handful of the sliced cube steak, followed by another slice of cheese, and finally the cheese-topped ham. Now that the foundation has been laid complete the masterpiece.
Top your sandwiches evenly with the lettuce, tomatoes, and red onion slices. Press a handful of shoestring potatoes on top of the melted cheese so they stick. Press the two halves together to complete the tripletas.
Enjoy your tripletas with chips and your favorite soft drink.
Make Ahead Options:
After seasoning the meat you can transfer the steaks to a food storage container and refrigerate it for 24 hours.
You can also transfer the seasoned meat to a freezer storage bag and freeze it for up to 2 months. If you choose to freeze the meat, thaw it overnight in the fridge before searing it for the tripletas.
The mayo-kechu spread can be made a week ahead and stored in a container in the fridge. It's a great dip for fries or condiment for burgers.
Wrap assembled sandwiches in a layer of sandwich wax paper, followed by a layer of heavy-duty aluminum foil. The wax paper prevents the bread from sticking to the foil, which retains a lot of the sandwich's heat. I only recommend holding assembled sandwiches for an hour or less.
Swaps and Substitutions:
Add chopped chicken thighs or replace one of the meats with them: Season and marinate the chicken the same way as the cube steak. Cook it for 5 minutes per side, instead of 3.
Replace the pernil with sliced leftover turkey.
Swap the sliced ham for hard salami, prosciutto, pancetta or cooked bacon.
Chopped brisket and/or pulled pork can replace the cube steak and pernil.
Instead of making four individual sandwiches, make a big footlong tripleta. Use two foot-long rolls and complete the recipe according to the instructions. Assemble everything onto the two sandwiches. Cut the assembled sandwich into smaller portions for a party or more generous slices for a smaller crew.
Wrap any leftover sandwiches and store it in the fridge for 1 day.