In a bowl, toss the steak cubes with Cajun seasoning, salt, and pepper until evenly coated.
Heat olive oil in a large skillet over medium-high heat. Once hot, add the steak cubes in a single layer. Cook for 2-3 minutes without stirring to get a nice sear.
Flip the steak bites and cook for an additional 2-3 minutes for medium-rare, or longer if desired. Remove the steak bites from the skillet and set aside.
In the same skillet, reduce the heat to medium and add the butter. Once melted, add the minced garlic and sauté for about 30 seconds until fragrant.
Return the steak bites to the skillet and toss to coat them in the garlic butter. Cook for an additional minute to heat through.
Remove from heat, garnish with fresh parsley, and serve immediately.