Hi C- again as above - less cooking the better. Seconds a side on a searing hot griddle/pan, with the middle still pink is my suggestion..
- you can have it raw too of course as a 'carpaccio' - put the steaks in the freezer for 30 mins to firm up, slice wafer thin over a seasonal salad and nice dressing like honey and lemon....this works best if you have a fillet, not the steak cuts, so you can get nice round slices....
1000 suggestions here to play withif you want some ideas:
http://www.astray.com/recipes/?search=tuna
Tuna when fresh is able to take quite stong flavours so the chilli etc suggestions are a good idea. Sharp flavours work best I think, rather than creamy sauces, and it marries well with crispy bacon as a further taste..especially in salads like a nicoise, or with crumbled cooked smoky bacon and asparagus.....
The meat of the fish should be good and red. If it is at all brown, leave the stuff alone and avoid it as it is old and tired and won't have the proper texture and flavour anyway.
Much better to have it cut off a 'joint' from a fishmonger if you can, than on a tray under plastic film in a s/market as you don't know how long its been sitting there....