Prep Ingredients: Dice the steak and potatoes into small, even-sized cubes. Mince garlic and prepare herbs if using.
Cook Potatoes: Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add potatoes in a single layer, season with salt and pepper, and cook for 10–12 minutes until golden and tender. Stir occasionally, then set aside.
Sear Steak: Pat steak dry with paper towels. Add 1 tablespoon oil to the same skillet over high heat. Sear steak in batches for 2–3 minutes per side until browned. Set aside.
Make Garlic Butter: Lower heat to medium. Add butter to the skillet. Once melted, stir in garlic and herbs. Cook for 30 seconds until fragrant.
Combine & Finish: Return steak and potatoes to skillet. Toss everything in garlic butter to coat. Cook for 1–2 minutes more. Garnish with parsley and serve.