Toss the cubed sirloin in a bowl with the seasoning until evenly coated.

Heat the olive oil in a large cast-iron skillet over medium-high heat until shimmering.

Add the meat to the skillet in a single layer. Sear undisturbed for 2 minutes to develop a crust.

Flip the pieces and cook for 1 more minute.

Reduce heat to medium-low. Add the butter and minced garlic to the skillet.

Toss the meat in the foaming butter sauce for 1 minute until fragrant and cooked to your preferred doneness.

Garnish with fresh parsley and serve warm with mashed potatoes.