No expert here, but if your definition of "sear" is same as mine, here is my method. For 50 years my father has seared steaks on a piece of plate steel on an open outdoor fireplace. I adapted this to my BGE using plate steel I purchased from an alloy business - described as "carbon steel" 1/8-inch thick or 3/16. I initially got the triangle looking piece, but then the 1/2 circle. I kept the small corner pieces if I am only doing a couple of steaks.
At the temperature others suggest, about 2 minutes a side - RARE. Heat steel plate on top of grid. Throw down lots of butter on the steel and course salt, garlic or your choice of seasoning. You'll get a seared crust. I am not one to get excited about grill marks, as I see them as marketing. http://s1220.photobucket.com/user/tampabayhawk/media/SteelPlates_zpsa9de43f1.jpg.html
Above shows the corner pieces, triangle piece, 1/2 circle piece and stone (for size comparison). When I had steel cut ---- I took grid with me so they can cut close to same size.http://s1220.photobucket.com/user/tampabayhawk/media/DSC00104_zps4781934e.jpg.html
Above - steaks on steel.
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