Flank Steak: Combine the adobo sauce, oil, salt, lime juice and sugar into a bowl and whisk together and transfer to a plastic bag along with the flank steak. Move the ingredients around so the steak is covered and marinate while prepping the other ingredients or overnight.
Aioli: In a small bowl whisk together the mayonnaise, salt, lemon juice and garlic until combined and refrigerate until ready to serve.
Add some about 1 ½ cups of oil to a 10” cast iron skillet and heat until it reaches about 350° to 375° and add in ½ of the plantains and cook for 3 to 4 minutes per side. Place them on a sheet tray lined with paper towels to let drain and cool for few seconds before mashing with the back of a pan or a tortilla shell maker.
Place the smashed plantains back into the fryer and cook for 2 minutes or just until crispy. Set aside and repeat with the other ½ of the plantains.
Once everything is prepped up add the flank steak to a very large sauté pan over medium-high heat and cook until a medium-rare internal temperature is achieved, about 7 minutes per side.
Set aside to rest for 2 minutes and then slice very thin on a bias and against the grain. Keep warm.
To Plate: Later up a fried plantain, American cheese, aioli, sliced flank steak, tomatoes, onions, aioli and fried plantain.