Preheat the oven to 180°C.
Mix the sesame oil, fish sauce, ginger, garlic and lemongrass in a bowl.
Cut the lime in half and squeeze out its juice into the mixture, then slice it into thin rings.
Put the lime slices in a baking dish.
Dip the bass fillet in the sauce, then lay them on top of the lime rings. Pour over the remaining sauce, then scatter the spring onions and chilli slices on top.
Season with black pepper, then cover the dish with foil.
Put the dish in the oven and bake for 10-15 minutes, until the fish is tender.
Scatter the coriander leaves on top and serve.