For the blue cheese butter: Whisk together the butter, blue cheese, chives, honey, mustard and lemon zest in a bowl until uniform. Season to taste with salt and pepper. Using a spatula, scrape out onto plastic wrap, then form into a log and refrigerate until firm, about 1 hour.
For the black powder rub: Toast the sesame seeds, peppercorns, poppy seeds and mustard seeds in a dry pan until fragrant, 1 to 2 minutes. Transfer to a small food processor, blender or spice grinder along with the salt, brown sugar, granulated garlic and dehydrated onion and pulse until finely ground. Or use a mortar and pestle. This is a great task for a guest!
For the rib eyes: Preheat the oven to 225 degrees F. Line a sheet pan with foil and fit a rack inside.
Brush the steaks with vegetable oil and coat in a good amount of the black powder rub. Place on the wire-racked sheet pan and roast until the internal temperature registers 115 to 120 degrees F, about an hour.
Heat a large cast-iron skillet over medium-high heat. Add a little vegetable oil to the bottom and sear the steak until properly charred, about a minute per side. (Don't forget to hold the steak upright with tongs to sear the edges.) Transfer to a warm plate. (See Cook's Note.)
Slice a medallion of the cold blue cheese butter and place it on top of each steak. Very carefully ignite a rosemary sprig with a torch to get it smoking (blow out any flame; you just want the smoke) and place it on top of the steak and butter. Immediately cover with a cloche or dome to trap in the smoke. Repeat with the remaining steak. Serve and slice tableside, if desired, into manageable pieces.
Servings 0