To dry brine the steak, sprinkle kosher salt liberally on all sides of the steak and allow it to sit elevated on a cooling rack over a baking sheet in the refrigerator for 4-24 hours
Remove the steak from the refrigerator
Rinse the steak with water and pat dry
Wrap the steak in paper towels while you prepare your grill
Preheat your grill for indirect cooking
Although your steak has been dry brined, you may want to consider adding 1-2 tablespoons of additional steak seasoning or BBQ rub with a low salt content
Using a leave-in digital thermometer, roast the steak over indirect heat and slowly bring the steak toward your ideal internal temperature (shoot for 115F)
As you approach your desired internal temperature, sear the outside of the steak over direct heat to further develop the bark and give the meat some char
Remove from the heat and wrap tightly in plastic wrap
Place the meat in the refrigerator to rest for a minimum of 90 minutes or as long as overnight
Heat your Blackstone griddle to medium-high heat and toast the Kaiser buns for 4-5 minutes until golden brown and set aside
Remove your steak from the refrigerator
Using a meat slicer or slicing knife, carefully slice your steak across the grain as thinly as possible
Place 6-8oz of steak on the Kaiser bun and top with the Blue Cheese Horseradish sauce Serve immediately