Cut the sirloin steak or ribeye into 1-inch cubes and season with salt and pepper. Let rest at room temperature for about 15 minutes.

Heat a large cast-iron skillet over medium-high heat and add enough olive oil to coat the bottom.

Add steak cubes in a single layer and sear for about 2 minutes without moving. Flip and cook for an additional 2 minutes for medium-rare.

Reduce heat to medium-low, add unsalted butter and minced garlic to the skillet. Stir for about 30 seconds until fragrant.

Return the steak bites to the skillet and toss in the garlic butter until well-coated. Garnish with chopped fresh parsley and serve hot.