Cut the steak into approximately 1 ½-inch pieces and pat them dry with a paper towel. Sprinkle with salt and pepper on all sides.

Heat a large (12-inch) skillet over medium heat for about 3 minutes, then add 1 tablespoon of butter. Add the steak bites in a single layer.

Sear the steak bites for about 3 minutes. Flip them over and sear until well browned and cooked to medium doneness, about 2 to 3 minutes more.

Turn the heat down to medium-low. Add the remaining 2 tablespoons of butter and chopped garlic to the pan. Sauté until the garlic is cooked through, about 2 to 3 minutes.

Remove the pan from heat. Add the steak bites back to the pan and toss to coat them evenly with the garlic butter. Transfer to a serving dish, sprinkle with parsley if using, and serve immediately.