Heat 1 tablespoon of oil in a large skillet over medium heat.
Add steak and season with sea salt and pepper. Cook until the steak is seared on one side, about 2 minutes.
Flip and cook for about 2 minutes more for medium.
Set aside on a chopping board, then slice thin.
Add the remaining oil to the pan, then add onion and bell peppers.
Season with oregano, sea salt and pepper. Cook, stirring often, until the onions and peppers are crisp-tender, about 5 minutes.
Add the steak back to skillet and toss to combine. Sprinkle with provolone then cover the skillet with a tight-fitting lid and cook until the cheese has melted, about 1 minute.
Arrange lettuce leaves on a serving platter.
Scoop steak mixture onto each piece of lettuce.
Serve warm and enjoy!