Low-Carb Seared Tuna with a Burnt Tomato & Caper Dressing

This is an easy and interesting dish starring just a few beautiful ingredients - spanking-fresh tuna, olive oil, capers, baby herb leaves and Rosa tomatoes at the peak of their ripeness.  I'm going to ask you deliberately to burn your tomatoes to make the dressing, and please do so with confidence, as it is the sweet charred flavour of the scorched tomatoes that gives the dish such a lovely flavour. Suitable for diabetics, and for anyone on a low-carb #LCHF regime.

Jewel-bright colours and just a few top-quality ingredients.

The idea for this dish came to me last weekend when I was cooking some tomatoes and tuna on the same griddle pan.  I tasted some of the sticky residue left by the tomatoes, along with a flake of tuna, and found the combination most agreeable.

The first time I made the dressing, however, I added too much balsamic vinegar, which overwhelmed the delicate taste of the fish.  The second batch, using just a teaspoon of vinegar, had the right balance.  The capers and rocket leaves are there to offset the natural sweetness of the tomatoes, and a squeeze of lemon juice at the end brings everything together.

I use pole-caught yellowfin tuna, which is presently green-listed on the SASSI database; albacore is another green-listed species.

This is a dish that can mostly be prepared in advance: see Cook's Tips, at the end of the recipe.

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Seared Tuna with a Burnt Tomato & Caper Dressing

1 x 400 g slab of fresh tuna
a little olive oil for frying
salt and milled black pepper
3 Tbsp (45 ml) capers, or more, to taste
a handful of baby wild rocket leaves (or the smallest leaves you can find in the packet)
a little fresh lemon juice

For the dressing:
8 Rosa tomatoes (or 12 cherry tomatoes)
1 tsp (5 ml) balsamic vinegar
5 tsp (25 ml) extra-virgin olive oil, plus extra for drizzling

Heat a griddle pan (ridged, if possible) until it is fiercely hot, almost - but not quite - on the point of smoking. Rub a film of olive oil over both sides of the tuna and season with salt and pepper. Sear the tuna for 45 to 60 seconds on both sides, or until the flesh is cooked to a depth of about 3 mm. Set on a plate to cool, then place in the fridge to chill while you make the dressing.

Sprinkle a tablespoon of olive oil onto the blazing hot griddle pan. Halve the tomatoes lengthways and place them cut side down on the pan. Leave them, undisturbed, for about two minutes, or until slightly charred on the underside.

Using a metal spatula or pallet knife (or similar: I use one of those flexible metal scrapers designed for filling cracks in walls), carefully loosen each tomato, making sure that the scorched surface doesn't stay behind on the pan surface. Flip them over and cook them for another minute or two, or until just soft, but not collapsed.

Put the hot tomatoes into a bowl (or a mortar) and lightly mash and squash them to release the juices.  Tear up the soft tomato halves into smaller pieces. Stir in the vinegar and olive oil and season to taste with salt.  Allow to cool.

Slice the tuna using an exceptionally sharp knife (this is easiest when it is cold) and arrange the strips on a platter.  Drizzle over the tomato dressing, and scatter the capers and rocket leaves on top.  Add a spritz of lemon juice - to taste - and a generous grinding of black pepper, and drizzle with a little more olive oil. Serve immediately with some fresh bread for juice-mopping.

Serves 4 as a starter.

I snipped some baby chives off a pot growing on my window and they added a delicate
oniony note to the dish.

Cook's Tips

• You can make this dressing (and sear and chill the tuna), well in advance, but I suggest you put the two together just before you serve the dish, or the acid in the tomatoes and vinegar may 'cook' the fish.
• If you're not a fan of rocket, use any small herb leaves of your choice: finely snipped chives, parsley tips, micro-herbs, and so on. 
• Capers aren't everyone's cup of tea, and if you're not a fan, I suggest you scatter some finely-chopped baby gherkins over the tuna. 

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