- Ÿ watermelon, peeled, flesh cut into 1cm/½in-thick slices
- 2 thin slices sourdough bread
- 4 x 50-75g/2-3oz fresh tuna loin steaks (ask the fishmonger for sushi-grade tuna)
- 1 lemon, juice only
- 2 tbsp very finely chopped fresh chives, plus extra to serve
- 1 shallot, very finely chopped, plus extra to serve
- knob of butter
- sea salt and freshly ground black pepper
- 2 tbsp extra virgin olive oil, to serve
- Scoop all of the watermelon slices into a re-sealable food bag. Add a pinch of salt and chill in the fridge for 2-3 days.
- When the watermelon is ready, preheat the oven to 150C/130C Fan/Gas 4.
- Toast the bread, then slice each in half widthways to create four slices, each with one toasted side and one untoasted side. Sandwich them between 2 clean baking trays. Bake in the oven for 5 minutes, or until hard and crisp. Remove the trays from the oven and set the bread aside to cool, still sandwiched between the trays.
- Lay a sheet of cling film onto a clean work surface. Place the tuna steaks on top and cover with a second sheet of cling film. Flatten the tuna steaks to a thickness of 2mm using a meat mallet or rolling pin. (Do this one steak at a time if it is easier.)
- Trim each piece of flattened tuna into a circle, using an upturned bowl as a guide. Set aside.
- Chop the tuna trimmings very finely and place them into a bowl. Squeeze over half of the lemon juice and add the chives and shallots. Season, to taste, with salt and freshly ground black pepper, then mix well.
- Heat the butter in a frying pan over a high heat until it starts to brown. Chop the watermelon slices into small pieces and add them to the pan in batches, frying for 1-2 minutes on each side, or until caramelised and heated through. Season with a pinch of salt. Remove from the pan and set aside on a warmed plate while you fry the remaining watermelon.
- To serve, spoon some of the tuna tartare onto each piece of toast. Place onto the serving plates and top with a piece of cooked watermelon. Turn over each circle of flattened tuna carpaccio, discarding the cling film, and place one circle alongside each toast. Brush each circle of tuna carpaccio with a little of the extra virgin olive oil, then sprinkle over the shallot and chives, squeeze over the lemon juice, and season, to taste, with freshly ground black pepper.