I just finished some research that I thought I'd pass along. I find general agreement that the best pastrami sandwich in L.A. is at Langer's on Alvarado. It is worth the rather risky trip (I wouldn't suggest it after dark, though you can order by phone and they'll take it to your car when you drive up). But we all wonder where they get their meat. Found it it is from R C Provisions in North Hollywood or Burbank. There was a recent pastrami tasting in Berkeley and the winning pastrami was from that provider. They don't sell direct to the public but one source is Niman Ranch where it is $8 a pound and can be ordered through their website. When steamed for two hours there is no equal in the world. Enjoy!