Prep the steak: Place the beef in the freezer for 20 to 30 minutes to firm up. Slice across the grain into very thin strips. Pat dry and season with salt, pepper, and a pinch of onion powder.

Slice the vegetables: Cut the bell peppers and onion into thin strips. If using mushrooms, slice them evenly so they cook at the same rate.

Brown the beef: Heat a large skillet over medium-high. Add 1 tablespoon oil. Sear the beef in two batches to avoid steaming, about 1 to 2 minutes per side, just until browned. Transfer to a plate.

Cook the veggies: Reduce heat to medium. Add butter to the skillet. Sauté onions and peppers with a pinch of salt for 5 to 7 minutes until softened and lightly caramelized. If using mushrooms, add them after 3 minutes and cook until they release moisture and brown.

Add garlic and season: Stir in garlic for 30 seconds. Sprinkle in smoked paprika and red pepper flakes if you like a little heat.

Deglaze: Pour in Worcestershire and beef broth. Scrape up browned bits from the bottom—this adds rich flavor without extra carbs.

Return the beef: Add the steak back to the skillet with any juices. Toss everything together and let it simmer 1 to 2 minutes until the liquid reduces slightly.

Cheese it up: Reduce heat to low. Layer provolone slices over the top or sprinkle shredded cheese evenly. Cover for 1 to 2 minutes until melted and bubbly. For extra creaminess, dot a few teaspoons of cream cheese on top before covering.

Taste and finish: Adjust salt and pepper. Garnish with chopped parsley if you like. Serve hot straight from the skillet.