Heat the oil in a frying pan until hot. Season the tuna, then add to the pan and fry for 30 seconds on both sides. Transfer to a plate and coat in the sesame seeds.
Put the salad leaves into a bowl, then add the mooli, edamame beans, tomatoes and onion.
Slice the tuna and arrange over the salad. Scatter the crispy shallots over the top.
Place the ponzu, vinegar, mirin, oils and ginger into a small bowl and whisk together. In a separate bowl, mix the mayonnaise and wasabi, then slowly pour the dressing into the mayonnaise, whisking until you have a creamy consistency. Pour over the salad before serving.