I too like raw tuna. I generally sear it lightly on both sides and keep the inside mostly raw. I only eat it with wasabe. As I understand it cultures that eat raw fish or meat generally eat it with something that kills bacteria and parasites. Ceviche is prepared with lime and hot peppers, sashimi with wasabe, and steak tartare with lemon, and rare meats with mustard (hotter than US mustard though) Do you have any info on this? I prefer my fish or meat rare to raw...don't eat beef, chicken, or pork though. Can you be sure that Sashimi grade tuna is ocean caught? Do you go to a seafood grocer you trust? Finally, is most tuna in average grocery stores farm raised?