Preheat your grill to high heat (about 450°F to 500°F).
Season the tomahawk steaks generously with salt and black pepper on both sides. Drizzle olive oil over the steaks and rub it in to ensure an even coating.
In a small bowl, combine the softened butter, minced garlic, parsley, thyme, rosemary, and lemon zest. Mix well until all ingredients are fully incorporated.
Place the steaks on the hot grill and sear for about 4-5 minutes on each side for medium-rare, or until they reach your desired doneness. Use a meat thermometer to check for an internal temperature of 130°F for medium-rare.
Once cooked, remove the steaks from the grill and let them rest for 10-15 minutes to allow the juices to redistribute throughout the meat.
After resting, slice the steaks and top each serving with a generous dollop of the herb butter. Serve immediately.