Line a steamer with paper bark, banana leaves or a circle of baking paper. Arrange the fish fillets in the base of the steamer and top with lemon myrtle spice and chopped garlic. Cover with a lid and steam for 5–6 minutes.
Remove the lid carefully and sprinkle with spring onion and lime juice.
Cover and steam for a further 20 minutes. Serve with wedges of lime and steamed rice.