Poached Salmon With Watercress Mayonnaise – Fishermen's Co-op

Ingredients

• 1 Carrot, chopped
• 2 Celery stalks, chopped
• 1 Onion, sliced
• 1 Small fennel bulb, sliced
• 2 Flat-leaf parsley stalks, bruised, plus 2 tbsp chopped leaves
• 400 ml White wine
• Pared zest of 1 lemon
• 1 tsp Whole black peppercorns
• 1 kg Piece skinless salmon fillet
• 1 kg Chat potatoes, peeled
• 20 g Unsalted butter
• 3 Egg yolks
• 1 tbsp Dijon mustard
• ½ tsp Lemon zest
• 1 tbsp Lemon juice
• 1 cup (250ml) extra virgin olive oil
• 2 cups (50g) picked watercress leaves, finely chopped, plus sprigs to serve