Just as much as I easily find good cuts of meat in the Haringey wing of Seven Sisters, well sourced tasty fish is equally as impossible to find. So when I crave it, I make it a proper treat, spending a bit more, but trying to find some sustainably sourced fish. In this case, I got a chunk of tuna from Wholefoods, together with some sea asparagus, and I planned to make something very special with them. Sauce Messine is a traditional French sauce used for fish – it’s in Elizabeth Davis’ book and I’ve made it a few times, although I almost never have the exact ingredients needed. As usual, I have allowed myself to make some adjustments and the result was simply delightful. This recipe serves two.