1 Preheat the oven to 350°F. Lightly grease a 10×10 casserole dish (for a thicker pastelón) or 9×13 casserole dish (for a thinner pastelón) with nonstick cooking spray or butter.
2 Prepare the plantains: Cut off both ends from the plantain, then use the tip of your knife to cut a slit down the back. Using your two thumbs, remove the peel from the plantain and discard the peel.
Once you’ve peeled all the plantains, slice each one in half down the length. Separate the two halves and flip them onto their flat sides to create a stable base. Place your palm flat on top of the plantain, and use a sharp knife to slice parallel to the cutting board and cut the plantains into very thin slices (about 1/4-inch thick). Set aside.
(Alternatively, you can use a mandoline to slice the plantains thinly, but be careful because the plantains are soft and the mandoline is sharp!)
3 Fry the plantains: In a large skillet, heat the vegetable oil to 300°F over medium heat (check the temperature with a candy thermometer or instant-read thermometer). Line a plate with paper towels to drain the plantains after frying, and set next to the stove.
Place four or five slices of plantains into the oil and fry for about 1 1/2 minutes on each side, or until the plantains have a browned slightly. Remove from the skillet to the paper-lined plate to drain. Continue frying the remaining plantains.
4 Cook the beef: Drain all but 1 tablespoon of oil from the pan you used to fry the plantains. Return the pan to the stove and heat over medium-high heat. Add the ground beef and season with the adobo and sazón.
Continue to cook the meat, breaking it up into crumbles, for 6 minutes or until browned. Drain the meat by pouring it into a colander, but leave a bit of the grease in the pan to cook the vegetables.
5 Cook the vegetables: Return the empty pan to the heat and cook the onions, bell pepper, and recaito for 3 minutes or until glossy. Add the olives, capers, and dried oregano, and cook for 2 more minutes.
6 Finish the filling: Return the ground beef to the pan with the vegetables, along with the tomato sauce, and then stir to combine. Bring the mixture to a simmer, then remove the pan from the heat.
7 Assemble the pastelón: Cover the bottom of the casserole dish with a single layer of the fried plantain strips. Spoon a 1-inch layer of the ground beef mixture onto the plantains. Top with 1/2 cup of shredded cheese. Repeat with another layer of plantains, meat, and cheese (reserve the remaining 1 cup of cheese). Top with a final layer of plantains.
8 Add the egg layer: In a small bowl, whisk together the eggs and baking soda until frothy. Pour this mixture over the plantains.
9 Bake the pastelón, uncovered, for 25 minutes. Remove from the oven and top with the remaining cup of cheese. Return the dish to the oven and cook for an additional five minutes, until the cheese has melted.
10 Cool and serve: Remove the pastelón from the oven. Allow it to cool for at least fifteen minutes before slicing and serving, which helps it maintain its shape when sliced.
Leftovers can be stored, covered, in the refrigerator for up to three days. To reheat, cut a portion and place either in the microwave or the oven until warmed through.