450 gmkipfler potatoes, scrubbed and sliced150 gmbaby green beans, trimmed1½ cups(loosely packed) frisée2 tbspolive oil4150gm pieces skinless sashimi-quality tunaTo taste:lemon juiceOlive vinaigrette70 gmpitted black olives½ cup(firmly packed) flat-leaf parsley2garlic cloves, finely chopped70 mlextra-virgin olive oil1 tbspred wine vinegarJuiceof ½ lemon, or to taste
Cook potato in a saucepan of boiling salted water until tender (15-18 minutes), drain and set aside to cool slightly.
Meanwhile, blanch beans until bright green and tender (1-2 minutes), drain, refresh, halve lengthways and transfer to a bowl. Add frisée and refrigerate until required.
For olive vinaigrette, pulse ingredients in a food processor until semi-finely chopped, season to taste and set aside.
Heat oil in a large frying pan over medium-high heat. Season both sides of each piece of tuna, add to pan and sear until browned (1-1½ minutes), turn and cook other side until browned (1-1½ minutes). Transfer to serving plates, squeeze a little lemon juice over.
Add potato to bean mixture, season to taste and toss to combine. Transfer to serving plates, drizzle with resting juices from tuna, spoon olive vinaigrette over everything and serve.