Pat the steak cubes dry with paper towels. Season them evenly with kosher salt and black pepper.
Place a large cast-iron skillet over high heat until very hot. Add the olive oil and swirl it around to coat the bottom.
Arrange the steak cubes in a single layer without overcrowding the pan. Sear for 1–2 minutes until a deep brown crust forms, then flip and cook the other side.
Transfer the steak bites to a plate and let them rest briefly while you prepare the garlic butter.
Reduce the heat to medium-low and add the butter to the skillet. Allow it to melt completely.
Stir in the minced garlic and cook for 30–60 seconds, stirring constantly until fragrant. Avoid browning or burning the garlic.
Return the steak bites and any accumulated juices to the skillet. Toss everything in the garlic butter until well coated.
Remove the skillet from the heat, sprinkle with fresh chopped parsley, and serve immediately while hot.
