Preheat the oven to 200 C. Mix the shallot, garlic, ginger, lemon grass, spring onion, fish sauce, tamari and half the lime juice together.
Grab some parchment paper place half the pak choi on one and the other half on the other. Place fish fillets on top of each of them.
Pour over the dressing equally over both. Wrap up the parchment and pop in the oven for 10 minutes. Rinse the rice noodles, cook as per pack instruction.
Serve together topped with the cashews