Interesting you don't like the thought of raw kahawai. It makes excellent sashimi. I have served a plate of sashimi to friends which had snapper, john dory, trevally and kahawai sashimi on it. All agreed the kahawai was best. As usual - has to be very fresh - kahawai in particular doesn't like waiting to be used. If you are into sashimi, I suggest you try the kahawai. You might be pleasantly surprised.

What do you marinate it in? How do you cut it i.e. across or with the grain?

I just bleed straight away,fillet and cut out blood line,cube it and mix with lemon/onion/salt,pepper,chopped tomatoes leave for 12hrs or more and an hour before serving tip in a can of coconut milk. or just soak in lemon/onoin. left longer the better.

It makes excellent sashimi... when fresh
There is a difference between raw As in using lemon juice/ acids and marinated
Raw is when just outside is pickled and marinated is cooked right thru As CatchaLot mentions above.. we just grab a larger piece open it up, then when the center is just changing colour, drain off the pickle (lemon juice) quick rinse then add the capsicum, tomatoes chives  coconut creme.. the concentrated stuff in cardboard containers without water and additives is the best

Will dig the receipy (s) later

Cut the blood lines out.. very sharp knife shaves it easy.
 Cut lengthways then cube