Pat steak dry with paper towel. Cut steak into 1-inch cubes so that they're small,bite-sized pieces. Season generously with salt and pepper. *
Heat a large skillet over medium-high heat. Add the olive oil and let it heat until shimmering.
Add the steak cubes in a single layer. Sear for 2-3 minutes per side, or until a golden crust forms. Work in batchesif necessary to avoid overcrowding the hot skillet. Remove cooked steak and set aside.
In the same skillet, add the butter. Turn the heat down to medium, and stir butter continuously so it doesn't burn. Once melted, add garlic and red pepper flakes. Cook for approximately 30 seconds until fragrant.
Return the seared steak bites to the skillet and toss them in the garlic butter sauce. Cook for an additional 1-2 minutes, until steak pieces are fully coated. Serve immediately with chopped parsley as a garnish.