Honolulu-based Maguro Brothers Hawaii specializes in super fresh fish and poke, and they cater too. Brothers Junichiro and Ryojiro Tsuchiya source their fish from the nearby Honolulu Fish Auction (see last link below). This is the brothers' "Hawaiian Limu Poke" (limu means seaweed, and they typically use "Ogo" limu). While you can use a range of fish for poke, including salmon and octopus, Maguro Brothers' specialty seems to be high-quality ahi tuna.
See more about their restaurant via the links below.