Me and A were sort of recreating a Cadiz recipe with a red wine reduction and  fully cooked tuna, rather than the rare/raw versions that have become synonymous with fresh tuna.   Finished with rendered bacon, cooked off mushroom and red wine from the marinade sauce.... well.... the tuna had been marinated in this red wine overnight and the fish was so fresh it was almost jumping out of the water when I bought it.  The fish was a dream  to work with.  The result with sauce, very very very good.  Sour, sweet, salty, sharp with texture and full meaty flavour.  With fish.   WFT?  Very delicious.  

Tuna, marinaded and cooked before being added back to the sauce

The tuna with the sauce and baked potato.  AGREE!  NOT PRETTY. But it tasted unreal.