Preheat the oven to 425°F (220°C). In a large bowl, toss the cut potatoes with olive oil, salt, and pepper until evenly coated. Spread the fries in a single layer on a baking sheet. Bake for 30-35 minutes, turning halfway through, until golden and crispy.

Season the top sirloin steak with salt and black pepper on both sides. In a large skillet over medium-high heat, melt 2 tablespoons of butter. Add the minced garlic and sauté for about 1 minute until fragrant. Place the steak in the skillet and sear for 4-5 minutes on each side for medium-rare, basting continuously with the garlic butter. Remove the steak from the skillet and let it rest for 5 minutes before slicing.

In the same skillet, add the beef broth and scrape up any browned bits from the bottom. Stir in the crushed peppercorns, Worcestershire sauce, and Dijon mustard. Bring to a simmer and reduce for about 5 minutes. Add the heavy cream and continue to simmer for another 3-4 minutes until slightly thickened. Season with salt to taste.

Slice the rested top sirloin and arrange it on plates. Drizzle the rich brown peppercorn sauce over the steak. Serve with the golden skin-on fries on the side, garnished with fresh parsley.