Step 1

Place salmon fillets in a saucepan and add enough water to cover salmon by 1cm. Add peppercorns, salt flakes and half the lemon juice and place over medium heat.

Step 2

Bring to a simmer, then remove from heat. Turn the salmon fillets and leave to poach in the water for 8 minutes or until just cooked through.

Step 3

Drain, discarding liquid. Set salmon aside. Bring a large pan of salted water to the boil over high heat. Cook the pasta according to the packet instructions, then drain and set aside.

Step 4

Whiz peas, watercress, walnuts, pecorino and half the lemon zest in a food processor until combined. Add oil and half the remaining lemon juice. Whiz to a paste.

Step 5

Season, adding a little more lemon juice to loosen, if needed. Transfer pesto to a large bowl. Add the pasta and toss to combine.