Dry and salt the steak don’t skip this. Pat the steak cubes completely dry with paper towels, then season them with the salt and let them sit uncovered on a plate for 10 minutes. This step is the one thing that separates steakhouse-style bites from gray, steamed ones: any surface moisture left on the meat turns to steam the second it hits a hot pan, and steam prevents browning. Ten minutes of air-drying and salting pulls that moisture to the surface and lets it evaporate, so the outside of the meat sears instead of simmers.
Par-cook the potatoes. While the steak rests, add the potatoes to a pot of salted water, bring to a boil, and cook for 6–7 minutes, just until a fork slides in with a little resistance. Drain well and let them steam-dry in the colander for a minute this helps them crisp instead of turning soggy in the skillet.
Sear the potatoes. Heat the olive oil and 1 tablespoon of butter in your skillet over medium-high heat until shimmering. Add the potatoes cut-side down in a single layer and let them cook undisturbed for 4–5 minutes, until deeply golden. Pro tip: resist the urge to stir them early moving them too soon is the main reason home-cooked potatoes end up pale instead of crisp. Remove the potatoes to a plate and tent loosely with foil.
Sear the steak in batches. Add 1 tablespoon of butter to the same skillet and let it get hot again. Add the steak cubes in a single layer, working in two batches if needed so you’re not crowding the pan. Sear for 2–3 minutes per side, until a deep brown crust forms and the internal temperature hits about 130–135°F for medium-rare. Crowding the pan here is the second most common way this dish goes wrong too many cubes at once drops the pan’s temperature and you’re back to steaming instead of searing.
Build the garlic butter. Lower the heat to medium, return all the steak to the pan, and add the remaining 2 tablespoons of butter along with the garlic and herbs. Stir constantly for about 45 seconds, just until the garlic turns fragrant and golden not brown, which turns bitter fast.
Bring it together. Return the potatoes to the skillet, toss everything gently in the garlic butter for another minute so the potatoes soak up flavor, then taste and adjust salt and pepper. Finish with fresh parsley and serve straight from the skillet.
