Historically Hawaiian fisherman would slice fresh fish into bite sized pieces (poke) and season it with a little sea salt and seaweed. Nowadays in the Hawaiian Islands you can find hundreds of variations of poke everywhere, from the local grocery store to exclusive restaurants like Nick's Fish Market in Maui. (We had an amazing dinner at Nick's on our honeymoon in 2007 and highly recommend putting that on your "to do" list if you go there on vacation. )
This Ahi Poke recipe exemplifies perfection in simplicity. Simple to make and simply melts in your mouth. Once you have made it you can experiment with other seasonings and fish if you like. And, for my fellow foodie adventurers, celebrity chef Sam Choy holds an annual Poke Contest in Keahou, HI. Check out his facebook page for details.
FYI- Here is an interesting article on what is considered sushi grade, you may be surprised. I get my Ahi in the freezer section at our local HMart.