Place halved baby potatoes in a pot of salted cold water. Bring to a boil and cook for 12 to 15 minutes, until just fork-tender but still holding their shape. Drain well and allow to steam dry in the colander for 1 to 2 minutes.

Pat the steak cubes completely dry with paper towels. Season on all sides with salt, black pepper, garlic powder, smoked paprika, and onion powder.

Heat a large cast iron skillet over high heat until smoking. Add the olive oil and 1 tablespoon of butter. Once the butter foam subsides, add the steak bites in a single layer, working in batches if needed to avoid crowding the pan.

Sear steak bites for 1 to 2 minutes per side until deeply browned on the outside. Remove to a plate, cover loosely with foil, and set aside.

Reduce heat to medium-high. Add the parboiled potatoes to the same skillet, cut side down. Cook undisturbed for 3 to 4 minutes until golden. Flip and cook another 2 to 3 minutes. Season with a pinch of salt and pepper.

Push the potatoes to the edges of the pan and reduce heat to medium. Add the remaining 3 tablespoons of butter to the center. Once melted, add the minced garlic and thyme. Stir constantly and cook for 60 seconds until fragrant.

Return the steak bites and any collected juices to the skillet. Toss everything together in the garlic butter and cook for 1 more minute to warm through.

Remove from heat, scatter fresh parsley over the top, and serve immediately.