The first indirect low & slow phase went as usual, but I added a 10" cast iron skillet and lid to the grill to preheat. The lid was not covering the skillet. It was placed directly on the grill side by side with the skillet.
The second phase was normal. I removed the steak, opened all of the vents wide open and allowed both the skillet and the lid to reach screaming hot temps. (my infrared thermometer read 800+ surface temp on the cast iron at one point)
The first side of the steak seared in the skillet for 1 minute, Once I flipped the steak, I added the blue cheese mixture and covered the steak with the screaming hot cast iron lid for another minute.
SUCCESS! Adding the super hot cast iron lid forced a broiler like heat down onto the cheese, melting it & making it almost crusty. At the same time finishing the sear.