Dice equal amounts of fresh salmon and tuna and leave to cool in a bowl in the fridge. Process the lemongrass, red onion, lime leaf, red chilli, coriander, basil, ginger, tamari, fish sauce, sesame oil and fresh lime juice until smooth.
Mix with the fish and leave for 1 hour for the flavours to develop.
Remove from the fridge about 20 minutes before you want to start cooking and mix with one or two egg whites. Roll into balls or cakes and put in the freezer on a baking sheet for about 15 minutes.
Roll the fishcakes in sesame seeds and then pan-fry for 30 seconds on each side before transferring to an oven to cook for 15 minutes at 180°C until fully cooked. Serve with lime wedges.