Preheat your oven to 425°F for roasting the potatoes.
Dice the potato into small cubes; toss with a little salt, pepper, and a drizzle of olive oil if desired.
Spread the potatoes on a baking sheet and roast in the oven for 20-25 minutes until crispy and golden, stirring halfway through.
While the potatoes roast, pat the steak dry and season generously with salt and pepper.
Heat a heavy skillet (preferably cast iron) over medium-high heat until very hot.
Place the steak in the skillet and sear for about 3-4 minutes on each side for medium-rare, adjusting time to reach your preferred doneness.
In the last minute of cooking, add the minced garlic (or crushed garlic clove) and unsalted butter to the pan, spooning the melted garlic butter over the steak.
Remove the steak from the skillet and let it rest for a few minutes while the potatoes finish roasting.
Slice the steak against the grain, plate alongside the roasted crispy potatoes, and garnish with fresh parsley if using.
Serve immediately and enjoy your balanced, satisfying meal.