Directions
Preparation:25min  ›  Cook:2hours  ›  Ready in:2hours25min 

1. Salmon: Before you start, remove the salmon from the fridge and bring up to room temperature.
2. Preheat the oven to 230 degrees C. Place a large rack over a large baking tray (large enough to support as much of the salmon as possible). Cut two large pieces of tin foil, large enough to form a roomy tent around the salmon when needed. Lay the bottom piece of foil on the rack. Place the other sheet of foil aside.
3. In a bowl, combine the watercress, dill, parsley and the lemon juice then season well, drizzle with olive oil and toss with your hands. Rub the fish generously inside and out with salt, pepper and olive oil. Lay a third of the watercress dill mixture on the tin foil as a bed for the salmon, stuff a third of it into the fish cavity then lay the remainder on top of the fish. Place the second piece of tin foil loosely on top then seal the edges of the two pieces together to form a tent.
4. Bake in the oven for 15 minutes at the preheated temperature, then lower the temperature to 180 degrees C and cook for about a further 90 minutes or until the fish has an even pink colour throughout. The exact timings will depend on the thickness of the fish, to ensure that you don't overcook it, you can remove the fish slightly underdone and allow it to continue steaming in its tent until evenly pink throughout.
5. Mousse: Meanwhile, to make the mousse combine all of the ingredients in a food processor and blend until smooth. Chill in the fridge.
6. To Serve: Remove the salmon from the oven and remove the lid of the tent. Allow to rest for 5 minutes. Cut fillets from the fish, one side at a time, running the knife flat along the skeleton of the fish and serve hot, or cold, with the chilled mousse.