1. Slice the spring onion lengthways into long, thin strips. place the spring onion in a bowl of cold water and soak until ready to serve (slices will curl).
2. To set up a makeshift steamer, choose a large, wide and deep pan with a tight-fitting lid. fold and scrunch a piece of foil into a long snake shape. then coil the shape to form a trivet. place in the bottom of the pan.
3. Place fish fillets onto a plate that is smaller than your pan and top with ginger.
4. Combine soy sauce and lime juice, then pour the mixture over the fish.
5. Place the plate of fish on top of the foil trivet in your pan. pour water into the pan (being careful not to pour any on the plate) until it comes to just below the bottom of the plate. turn the heat on high. once the water starts to steam, place the lid on. cook for about 12 minutes (or a bit longer for salmon) or until the fish fillets are cooked (they will easily flake when poked with a fork).
6. Just before the fish is ready, place the vegetable oil and the sesame oil in a small saucepan. heat until a wooden spoon causes bubbles to form when placed into the oil. turn the heat off but keep the oil warm on the stovetop.
7. Use a tea towel to protect your hands as you carefully remove the hot plate of fish from the pan. top with spring onion. pour the hot oil over the spring onion to sizzle and cook the onion a little. top with chilli slices and serve with steamed rice.