Pat the steak cubes dry and season all over with salt and pepper.
Heat the olive oil in a large skillet over high heat until shimmering.
Add the steak in a single layer and sear for 2-3 minutes, turning to brown all sides. Work in batches if needed. Transfer to a plate.
Lower the heat to medium and add the butter, garlic, and thyme. Cook for 30-60 seconds until fragrant.
Return the steak to the skillet and toss to coat in the garlic butter. Cook 1 more minute.
Sprinkle with parsley and serve immediately.