Place lemon zest in a small pot with oil and cook over lowest heat until zest sizzles very gently and begins to shrivel (10-15 minutes). Don’t let it go dark brown. Discard zest and allow oil to cool.

Place watercress or rocket in a strainer or colander and either dip into a pot of boiling water then into cold water, or pour boiling water over to wilt then cool under cold water. Drain, squeezing firmly to remove all excess moisture (you should be left with about half a cup). Add watercress and salt to cooled oil and whizz with a stick blender to a very fine purée (a food processor won’t give a fine enough texture). Store in a jar in the fridge for up to a week until needed.

Open out squid tubes and score the underside in a crisscross pattern with a sharp knife. Cut into pieces about 5cm x 3cm. Combine in a mixing bowl with 2 tbsp of the Rocket and Lemon Oil and the chilli flakes and allow to marinate for 20-30 minutes in the fridge.

Heat a heavy-based griddle pan or barbecue hotplate. Season squid with salt and pepper and sear in batches over high heat, cooking scored-side down first, until squid changes colour (about 1 minute each side). Transfer cooked squid to a large mixing bowl and stir in lemon juice. Pile rocket, spinach or watercress onto a serving platter and top with warm squid. Scatter with parmesan and drizzle with the remaining Rocket and Lemon Oil.