In a large bowl, toss the potatoes with olive oil, rosemary, salt, and pepper. Spread them in a single layer on a baking sheet.
Roast the potatoes for 20 minutes.
While the potatoes roast, pat the steak bites dry with paper towels. Season them with salt and pepper.
Heat a large cast-iron skillet over medium-high heat. Add 1 tablespoon of butter.
Once the butter is melted and sizzling, add the steak bites in a single layer. Sear for 1-2 minutes per side until browned. Do not overcrowd the pan; cook in batches if necessary. Remove steak from the skillet and set aside.
Reduce the skillet heat to medium. Add the remaining 3 tablespoons of butter.
Once the butter is melted, add the minced garlic and cook for about 1 minute until fragrant, being careful not to burn it.
Add the roasted potatoes to the skillet with the garlic butter. Toss to coat.
Return the seared steak bites to the skillet with the potatoes. Toss everything together.
Transfer the skillet to the preheated oven and bake for another 5-7 minutes, or until the steak is cooked to your desired doneness and the potatoes are tender and slightly crispy.
Garnish with fresh parsley before serving.
Notes
For best results when searing steak, ensure your skillet is hot and do not move the steak too much while it’s searing to achieve a good crust.
Cut potatoes into uniform sizes to ensure even cooking.
If you prefer softer potatoes, you can parboil them for 5-7 minutes before tossing with oil and seasoning.