Adjust oven shelf to the middle position. Preheat the oven to 200°C. Season the leeks and fennel with Green Onion Seasoning. In a saucepan, sweat the vegetables in the butter until just wilted. Add the peas, water and Fish Stock. Stir to mix. Spoon half the vegetables into a well buttered 25 cm x 18 cm ovenproof dish. Season and portion the fish. Lay the fish portions on the vegetable bed. Cover with the remaining vegetables. Bake for 15 minutes. To serve, garnish with the fennel fronds.