For the sauce:
1. Mix all the ingredients together and let it rest for a minimum of 1 hour so that the flavours can marry.
For the fish:
1. Mix together the ginger, lime juice and peanut oil, rub it onto the salmon and tuna, season with salt and freshly ground black pepper.
2. Add a little oil to a heavy based frying pan and sear the salmon and tuna on both sides, about 30 seconds on each side, remove from the pan and rest for 10 minutes.
3. With a very sharp knife slice the salmon and the tuna.
4. Divide the salad ingredients except the sesame seeds between 4 plates, top with seared salmon and tuna. Spoon over the sauce and sprinkle with sesame seeds. Serve.