01 - Combine the sirloin cubes with olive oil, salt, black pepper, and smoked paprika in a bowl. Mix thoroughly and allow to marinate while preparing potatoes.
02 - Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add quartered potatoes, season with salt and black pepper, and cook, stirring occasionally, until potatoes are golden brown and tender, about 12 to 15 minutes. Remove from skillet and keep warm.
03 - Raise the heat to high. Add the marinated steak pieces in a single layer, working in batches if needed. Sear undisturbed for 2 minutes, then turn and cook 2 to 3 minutes more, until well browned to preferred doneness. Remove steak from the skillet and set aside.
04 - Reduce skillet heat to medium and melt unsalted butter. Add minced garlic and dried thyme if using, sauté for 30 seconds until aromatic.
05 - Return potatoes and steak bites to the skillet. Toss thoroughly in the garlic butter until evenly coated and heated through, for approximately 1 to 2 minutes.
06 - Sprinkle freshly chopped parsley over the steak and potatoes immediately before serving.