Prep 20 minutes
Refrigerate 10 minutes
Cook 5 minutes
3 good-quality tuna steaks (about 200g each)
1 tsp peanut oil
1 cup cherry tomatoes, halved
1 red onion, peeled, halved and very thinly sliced
1 Lebanese cucumber, peeled in intervals and very thinly sliced
4 red radishes, trimmed and very thinly sliced
100g mixed baby salad greens
2 tbsp lemon juice
1 sheet nori, toasted and crumbled (see Tip)
1 tsp mixed black and white sesame seeds, toasted (see Tip)
For the dressing
2 tbsp mirin
1 tbsp sake
1/4 cup soy sauce
A pinch of caster sugar
1 tsp grated ginger
1 To make the dressing, combine the mirin and sake in a small saucepan and bring to the boil, then remove from the heat and transfer to a bowl. Add the soy sauce, sugar and grated ginger. Mix well and set aside.
2 If the tuna steaks are very big, halve them along the grain.
3 Heat the peanut oil in a heavy frypan until very hot and sear the tuna for about 20 seconds on each side. The tuna should still be quite raw in the centre.
4 Transfer the tuna to a press-seal bag and pour over a tablespoon of the dressing. Refrigerate for at least 10 minutes.
5 Slice the tuna across the grain into thin slices.
6 Toss together the tomatoes, onion, cucumber, radish and salad greens.
7 Place on a plate with slices of tuna.
8 Mix the remaining dressing with the lemon juice and pour over the tuna and salad. Scatter with the crumbled nori and sesame seeds.
TIP / To toast nori, hold a sheet with tongs and wave it over an open gas flame for just a few seconds until it becomes brittle. To toast black sesame seeds, mix them with a few white sesame seeds. When the white seeds turn golden, the black ones will be toasted, too.