Preheat oven to 200C/180C fan-forced. Line a large baking tray with baking paper.
Place butter, parsley, dill, tarragon, eschalot, capers, garlic and lemon rind in a small food processor. Season with salt and pepper. Process until combined.
Place 2 sheets of pastry, side by side, slightly overlapping, on a flat surface. Press pastry together to secure. Place on prepared tray. Sprinkle breadcrumbs, in a thin layer, lengthways along the centre of the pastry. Top with salmon. Spread salmon with garlic and herb butter. Drizzle with lemon juice. Place 2 remaining pastry sheets side by side, slightly overlapping, on a flat surface. Press pastry together to secure. Arrange over salmon. Leaving a 2cm border, trim edges of pastry around salmon. Press edges together with a fork to seal.
Brush pastry with egg. Lightly score the top of the wellington at 2cm intervals in a diamond pattern. Season with salt and pepper. Bake for 35 minutes or until pastry is golden and puffed and salmon is almost cooked through. Stand 5 minutes. Sprinkle with extra parsley and serve with lemon wedges.