Whole Fish in a Salt Crust with Gremolata

Ingredients

• Whole baked fish in a salt crust
• 2.4 kilogram cleaned whole ocean trout
• 3 kilogram coarse cooking salt
• 4 egg whites
• 1.5 kilogram baby new potatoes
• 4 clove garlic, unpeeled
• 1 tablespoon olive oil
• 10 sprigs fresh lemon thyme
• 350 gram watercress, trimmed
• Gremolata
• 1/2 cup finely chopped fresh flat-leaf parsley
• 1 tablespoon finely grated lemon rind
• 1 tablespoon lemon juice
• 1 clove garlic, chopped finely