You'll need (serves 2 hungry people):
1lb sushi-grade tuna
1 inch piece of ginger
1/2 bunch cilantro
3T roasted sesame seeds
1/4 red onion
1 lemon cucumber
1 large peach (mango would be fine here too if peaches aren't in season)
2 large handfuls arugula
rice wine vinegar
mirin cooking wine
chopped thai chile, optional
Mix dressing ingredients, adjusting quantities to taste.
Cut peach into small cubes and slice radish. Toss with arugula and set aside.
Slice the tuna into very small cubes, removing any white connective tissue as you go. Peel, de-seed, and chop cucumber into cubes of similar size. Peel and mince ginger. Mince red onion. Chop cilantro. Combine all in a bowl and sprinkle with sesame seeds.
Pour 2/3 of dressing on tartare and mix to coat. Toss the arugula salad with remaining dressing. Serve tartare in a scoop on top of arugula salad, garnished with more sesame seeds.