For the sea bass, heat a pan of water and place a steamer on top. Take a piece of foil. Scrunch up the edges to make a circle with a wall round the edge. Make it the right size to fit into the steamer.
Put a few leaves of bok choi onto the foil and place the fillets on top. Add more bok choi, ginger and lemongrass and pour over the sesame oil and soy sauce. Sit the foil in the steamer, put the lid on and steam for about four minutes until the fish is cooked (depending on the size of the fillets).
For the rice noodle salad, place the rice noodles in a large bowl, cover with boiling water and leave for two minutes. Alternatively cook the noodles according to the packet instructions.
Drain and place back in the bowl along with the spring onions.
To make a dressing, place the garlic, ginger, chilli, palm sugar, mint, coriander in a pestle and mortar and pound to a paste. Add the vinegar, lime juice and oil and pound some more.
Just before serving dress the noodle salad and mix.
To serve, place some of the noodles on each serving plate. Lift the fillets from the steamer and place them on top of the noodles. Pour the sauce from the foil into the pestle and mortar and mix it, then pour some over the fish.