Slice fish into fillets and sprinkle with salt. Set aside for 30 minutes.
Mix Japanese sake, soup stock (dashi), soy sauce and mirin (sweet sake) in a glass bowl. Heat in a Panasonic steam combi microwave at 1000W for 2.5 minutes.
Cut the white leeks into 3cm pieces and halve lengthways.
Slice the ginger thinly.
Line up clams and ingredients from step 1,3, and 4 on metal tray.
Pour the ingredients from step 2 onto step 5.
On the 'Steam 1' setting, cook the ingredients from step 6 for 20 minutes on the top rack.
As a finishing touch, drizzle olive oil and sprinkle over lime zest.