01 - Pat steak cubes dry with paper towels. Season all sides evenly with kosher salt and freshly ground black pepper.
02 - Heat olive oil in a large heavy skillet over high heat until shimmering.
03 - Add steak cubes in a single layer without overcrowding. Sear undisturbed for 1 to 2 minutes until a brown crust forms.
04 - Flip the steak cubes and cook for an additional 1 to 2 minutes to reach medium-rare doneness. Transfer steak bites to a plate and set aside.
05 - Reduce heat to medium-low. Add butter to the skillet, melt it, then stir in minced garlic and sauté for 30 seconds until fragrant.
06 - Return steak bites to the skillet and toss to coat evenly in garlic butter. Sprinkle with chopped parsley and optional crushed red pepper flakes.
07 - Serve immediately as an appetizer or main dish.