Grilled Tuna on Potato and Onion Salad

Fresh tuna is a beautiful, meaty fish, but if you would prefer not to use it or just can’t find anywhere to buy it, this dish can work very well with turbot, brill, bass and many other fish. The tuna medallions have a very similar texture to fillet of beef, and are cooked in a similar fashion. Tuna fillet eats best when cooked medium rare to medium.


  • 8 large onions, sliced
  • 2 tablespoons water
  • 350 g (12 oz) new potatoes, boiled
  • 175–200 ml (6–7 fl oz) Basic Vinaigrette
  • A few fresh basil and tarragon leaves, chopped
  • 4 medallions of tuna fillet, each about 175 g (6 oz)
  • 1 curly endive, separated, or a handful of lettuce leaves per person


Place the onions and water in a pan and allow to cook very slowly until the natural sugar from the onions starts to caramelize and then brown, stirring occasionally. This will take at least 1 hour of slow cooking.

Pre-heat the barbecue or grill to hot. Slice the warm new potatoes and sprinkle liberally with some of the vinaigrette. Mix with the onions and chopped herbs. This mixture should be kept just slightly warm.

The tuna would now best be cooked on an open barbecue to give a good grilled taste, but it can also be cooked under a pre-heated grill (or pan-fried in some butter and olive oil). It will take about 3–4 minutes per side, depending on the thickness of the fillet.

Spoon the potato and onion salad on to the centre of the plates. Dress the salad leaves with some of the vinaigrette. Sit some leaves on top of the potatoes and finish with the tuna. Spoon some of the dressing over and serve.