In a mixing bowl, combine molasses, smoked paprika, soy sauce, Dijon mustard, salt, and pepper. Mix well to create the marinade.

Place the sirloin steak in a resealable bag or a shallow dish and pour the marinade over it. Ensure the steak is well coated. Marinate in the refrigerator for at least 1 hour, preferably overnight.

While the steak is marinating, peel the russet potatoes and slice them into thin shoestrings. Rinse the sliced potatoes under cold water to remove excess starch. Pat dry with paper towels.

In a large pot or deep fryer, heat vegetable oil to 350°F (175°C). Carefully add the potatoes in batches and fry until golden brown and crispy, about 3-4 minutes per batch. Remove fries from the oil and drain on paper towels. Season with salt while hot.

Preheat a grill or skillet over medium-high heat. Remove the sirloin from the marinade, allowing excess to drip off. Grill or sear the sirloin for about 5-7 minutes per side for medium-rare, or until desired doneness. Let the steak rest for 5 minutes before slicing.

In a saucepan, melt butter over medium heat. Add whole black peppercorns and sauté for 1 minute. Pour in the heavy cream and bring to a gentle simmer. Stir in garlic powder and let it reduce for about 5 minutes until thickened. Season with salt to taste.

Slice the rested sirloin against the grain. Arrange on plates with shoestring fries on the side. Drizzle the peppercorn cream sauce over the steak and garnish with fresh parsley.