Most of the LB's I see in my corner of the world are round cuts but some are sirloin. I prefer the flavor of sirloin and try to get one special order cut for me when I can (Ingles will do it). I like about 3-4 lbs, about 1.5 inches thick. A marinade with both acid and oil helps with flavor and appearance. The real capper is to find the grain of the meat then cut across it, thinly, so the slices are guaranteed tender. I also do a reverse sear and give it a smoke bath for about an hour before I actually cook it
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