Remove the aged sirloin from the refrigerator and let sit on a wire rack over a plate for 45–60 minutes until it reaches near room temperature. Pat the steak dry thoroughly with paper towels to remove any surface moisture.

Season the steak evenly on all sides. Sprinkle the kosher salt, freshly ground black pepper and garlic powder, pressing lightly so the seasonings adhere. For best crust, apply salt immediately before cooking if the steak was not previously dry-aged with heavy surface salt.

Searing & Roasting

Preheat oven and pan

Preheat your oven to 400°F (205°C). Place a heavy oven-safe skillet (cast-iron preferred) on the stovetop and heat over medium-high until very hot, about 5 minutes.

Add the high-heat oil to the hot skillet and swirl to coat. Carefully place the steak in the pan away from you so the fat doesn’t splatter. Sear without moving for 2½–3 minutes until a deep brown crust forms.

Flip the steak and sear the other side for 2–3 minutes. Sear the edges by holding the steak with tongs and pressing each side to render fat, about 30–45 seconds per edge.

Add the unsalted butter, smashed garlic cloves, thyme and rosemary to the pan. As the butter melts, tilt the pan slightly and use a spoon to baste the butter and aromatics over the steak repeatedly for 30–60 seconds.

Transfer the skillet to the preheated oven. Roast until internal temperature reaches desired doneness: 115°F (46°C) for rare, 125°F (52°C) for medium-rare, 135°F (57°C) for medium. For a 1½–2 inch steak expect 4–8 minutes in the oven depending on thickness and starting temperature. Use an instant-read thermometer in the thickest part to check.

Resting & Finishing

Remove the steak from the oven and transfer to a cutting board. Tent loosely with foil and rest for 8–10 minutes (this allows carryover cooking and redistributes juices).

While the steak rests, if you want a pan sauce: place the skillet back on medium heat, pour off excess fat leaving about 1 tbs, add 1 cup red wine or beef jus, and scrape browned bits from the pan with a wooden spoon. Reduce by half, then whisk in 1 tbs cold butter off heat to finish the sauce; season to taste with salt and pepper.

Slice the steak against the grain into ¼–½ inch slices. Sprinkle with coarse sea salt and chopped parsley. Serve with pan sauce on the side or spooned over the steak.