For the steak marinade, in a quart mason jar, mix lime juice, vegetable oil, garlic paste, adobo, onion powder, oregano, cumin, and black pepper. Seal the jar tightly and shake vigorously for 40 seconds to 1 minute until ingredients are fully blended.
Infuse flavor into the steaks: Transfer the marinade to a shallow dish or a durable zip-top bag. Fully coat the ribeye steaks in the marinade, ensuring each side is covered. Seal tightly and refrigerate for at least 1 hour, or up to 12 hours for maximum flavor.
Prepare the mayo-ketchup: Mix together mayonnaise, ketchup, lime juice, granulated garlic, and adobo until smooth in a mixing bowl. Refrigerate the mayo-ketchup until ready to use, can be made ahead and stored in the fridge for up to 5 days.
Prepare the plantains: 20 minutes before searing the steaks, remove the stems by cutting 1/2 inch off each end of the plantains. Make a slit down the length of the plantain with a paring knife and peel it using your thumb. Slice the peeled plantains in half lengthwise. Repeat with the rest of the plantains.
Set up your frying station by filling a 12-inch frying pan with 2 inches of vegetable oil and heating it over medium heat. As the oil heats up, ready a draining station by placing a cooling rack over a sheet pan or lining a sheet pan with paper towels to soak up the excess oil. Keep your oven on "warm" to keep the tostones warm after frying.
Fry the plantains: When the oil hits 330°F, add 4 plantain slabs in two batches. Fry for 2 minutes, then flip with tongs. Fry for another 2 minutes or until a knife slides in easily. Remove plantains with tongs onto a sheet pan to drain excess oil. Repeat with remaining batch.
Take the steaks out of the fridge: Remove the steaks from the refrigerator to let them come to room temperature before smashing the plantains.
Prepare the plantains: Heat the frying pan with oil over medium-high heat. Lay a piece of parchment or wax paper over each plantain slab on a cutting board. Use a heavy pan to smash the plantains to a 1/3-inch thickness. Gently separate the flattened plantains from the board using a knife or spatula. Repeat the smashing process for the remaining plantains until they are all flattened.
- Refry the plantains: When the oil in the pan reaches 350°F (180°C, fry the flattened plantains for 2 minutes on each side until crispy and slightly browned. Work in batches of 2 or 3 to prevent overcrowding. Use tongs to remove the tostones from the oil and drain them on a rack. Place them on a sheet pan in the oven to keep warm.
Heat a 12-inch or larger skillet over medium-high heat, add 1 tablespoon of vegetable oil. Gently press the steaks onto the hot pan for an even sear. Cook for 4 minutes for medium-rare, then flip and cook the other side for another 4 minutes using tongs.
Rest the steaks: Take them out of the pan and let them sit for 5 minutes.
Create the jibarito sandwiches by generously spreading 1 1/2 tablespoons of the mayo-ketchup on each tostón. Layer 4 tostones with a slice of cheese, a piece of steak, lettuce, 2 slices of tomato, and some onion. Add another slice of cheese and top with the remaining tostón. Serve the jibarito right away. Enjoy this delicious dish and show your appreciation with a star rating!