Start by patting the sirloin steaks dry with a paper towel, ensuring they're ready to absorb the seasoning. Generously season both sides with salt and pepper, then allow the steaks to rest at room temperature for 30 minutes.

Heat a heavy skillet over medium-high heat until it's hot. Add a stick of butter and let it melt until it foams, looking for a slight browning. Sear the seasoned steaks for about 5-6 minutes on each side, until they reach medium-rare doneness, and allow them to rest afterward.

While the steak rests, slice the French baguette into even pieces, about 1-inch thick. Spread softened butter generously on each slice and sprinkle with salt, pepper, garlic powder, and dried parsley.

Preheat your air fryer to 360°F and arrange the buttered bread slices in a single layer. Toast for approximately 5 minutes or until the edges are golden and crispy.

Once the steaks have rested, slice them against the grain into thin pieces. Drizzle a few drops of Worcestershire sauce over the sliced steak.

In a mixing bowl, combine the sour cream with freshly grated horseradish to taste, along with a pinch of salt and pepper. Whisk until smooth and creamy.

To assemble, place a slice of steak on each toasted garlic bread piece. Generously top with the creamy horseradish mix, then garnish with fresh black pepper.