A fresh, thick tuna steak, seared around the edge, raw in the middle, served with a simple rocket salad with truffle oil new potatoes, is one of the finest meals I have eaten.
On that note, one of the problems with the pre-packed tuna steaks sold in supermarkets is that they are just not thick enough, e.g. only 15mm or so. Consequently it’s difficult/impossible to cook the outside while keeping most of the interior rare: I think the steaks need to be 25mm-30mm thick to get the best results.
A couple of suggestions to jazz it up a bit:
1. Some balsamic vinegar dizzled over the rocket or blended in the olive oil dressing, plus some shaved parmesan on top, gives the rocket salad a boost. You can shave the parmesan with a fancy mini-mandolin or a peeler.
2. Fennel butter works well with tuna: pound a teaspoon or so of fennel seeds with a mortar and pestle. Melt some butter in a small pan and add the crushed fennel seeds. As soon as the tuna is done and on the plate, turn the heat up under the butter, and when it is foaming pour the butter over the tuna.