In a bowl, mix the sesame oil, soy sauce, mirin, grated ginger, chopped cilantro, and toasted sesame seeds.

Cut the tuna into small cubes and add to the bowl. Season with salt and pepper, then stir to combine.

Divide the tartare among four plates. Serve immediately. If you like, you can add a squeeze of lime juice. Serve with fragrant white rice or a simple green salad.