Line a baking tray with foil, and brush/spray the base with half the oil. Put in an oven and heat to 200C.
Combine the soy, sake and fish sauce in a small bowl (I always use a ramekin for this) and mix thoroughly.
Peel and julienne the ginger, peel and thinly slice the garlic, and cut the chilli into thin angled slices.
Trim and slice the spring onions.
Once the oven has reached temperature, remove the hot baking tray and carefully place the cod loins on top. Pour over the marinate, and finely grind a little black pepper over them. Then, divide the chilli, ginger, and garlic between the two cod loins ad carefully place on top.
Finally, scatter the spring onion over the loins, drizzle the remaining olive oil and loosely wrap them in foil.
Bake in the oven for 15-20 mins