I went ahead and bought a dedicated vessel for the task and used it for my second go at a pair of steaks.  I remembered to pat the steaks dry before searing them, and really cranked the heat on the cast iron skillet.  My infrared thermometer was showing it at 600 degrees when I flopped them in.  I could have gone higher but I was afraid I would burn the seasoning off.They came out some better than my first go, there is almost no grey along the edges of the cut and the sear is better developed.