Heat 1 tablespoon of oil in a large skillet over medium heat, then add onion and bell peppers. Season with oregano, salt and pepper. Cook, stirring often, until the onions and peppers are tender, about 5 minutes. Remove peppers and onions from skillet and heat remaining oil in skillet.
Add steak in a single layer and season with salt and pepper. Cook until the steak is seared on one side, about 2 minutes. Flip and cook until the steak is seared on the second side and is cooked to your liking, about 2 minutes more for medium.
Add onion mixture back to skillet and toss to combine. Sprinkle provolone over steak and onions then cover skillet with a tight-fitting lid and cook until the cheese has melted, about 1 minute. Remove from heat.
Arrange lettuce on a serving platter. Scoop steak mixture onto each piece of lettuce. Garnish with parsley and serve warm.
Recipe by Cooking TV Recipes at https://cookingtv-channel.com/no-carb-philly-cheesesteaks/