Prepare the Chimichurri Butter: In a mixing bowl, combine the softened butter, parsley, oregano, garlic, red wine vinegar, red pepper flakes, salt, and pepper. Mix until well combined. Transfer to a piece of parchment paper, shape into a log, and refrigerate until firm.

Prepare the Steak: Preheat your grill or smoker to medium-high heat (about 400°F). Rub the Porterhouse steak with olive oil, then season generously with smoked paprika, dried oregano, garlic powder, onion powder, salt, and black pepper. Make sure to coat both sides evenly.

Smoke the Red Onion: Place the sliced red onion on a piece of aluminum foil and drizzle with olive oil, salt, and pepper. Wrap the foil tightly to create a packet. Place the onion packet on the grill or smoker for about 15-20 minutes until tender and infused with smoke flavor.

Grill the Porterhouse Steak: Once the grill is heated, place the Porterhouse steak directly on the grill grates. Grill for about 4-5 minutes on each side for medium-rare or until desired doneness. Use a meat thermometer to check for an internal temperature of 130°F for medium-rare.

Rest and Serve: Remove the steak from the grill and let it rest for 5-10 minutes before slicing. While the steak is resting, unwrap the red onions and set aside. Slice the steak against the grain and serve topped with smoked red onions and a generous dollop of chimichurri butter. Garnish with fresh oregano leaves.