Boil the potatoes until soft, then drain and mash while hot.
Flake the tuna and mix with the mashed potato, chilli, coriander, lemon rind, coriander leaves, chives and egg. Season with salt and pepper and add lemon juice to taste.
Shape the mixture into 8 fish cakes and flatten the tops and sides with a palette knife. Press the sesame seeds on to the fish cakes using the palette knife.
Heat the 2 oils together in a frying pan.
Fry fish cakes on both sides until golden.
Drain on absorbent paper and serve with hoisin sauce.
Place all the ingredients in a pan. Simmer until the flavours have blended.