Prep the steak. Lay the thin slices on a board and gently pound with a meat mallet to even thickness (about 1/4 inch). Season both sides with salt, pepper, garlic powder, and smoked paprika.

Slice the veggies. Cut the peppers and onion into thin, even strips so they cook quickly and roll up easily.

Sauté the veggies. Heat a large skillet over medium-high with a bit of oil. Cook peppers and onion with a pinch of salt until slightly softened and lightly charred at the edges, about 4–5 minutes. Transfer to a plate.

Assemble the roll-ups. Place a small bundle of peppers and onion near one end of each steak slice. Roll tightly and secure with a toothpick or short piece of twine.

Sear the roll-ups. Add more oil to the skillet and heat over medium-high. Place the roll-ups seam side down and sear on all sides until browned, about 6–8 minutes total. Reduce heat if needed to prevent burning.

Finish to tenderness. If your steak is thicker or you prefer more doneness, reduce heat to medium-low and cover for 2–3 minutes. Don’t overcook; you want the steak tender.

Make the garlic butter sauce. In a small saucepan (or the cleared skillet), melt the butter over low heat. Add minced garlic and cook gently 30–60 seconds until fragrant. Season with a pinch of salt, pepper, and optional red pepper flakes. Stir in a touch of lemon zest or juice if you like brightness.

Serve and garnish. Remove toothpicks, plate the roll-ups, and spoon the warm garlic butter over the top. Finish with chopped parsley.