Place a dry frying pan over a medium heat. Tip in the pine nuts and toast them for 2-3 mins, shaking the pan every so often so they brown evenly all over. Tip them into a small blender or food processor. No blender or processor? See our tip on how to make pesto the old-fashioned way.

Coarsely grate the Parmesan and add it to the pine nuts. Peel and crush the garlic and add that too. Pick the basil leaves off the stalks and drop the leaves into the blender/processor. Add a pinch of salt and pepper, 1 tbsp olive oil and 3 tbsp cold water. Blitz to make a coarse pesto. Taste and add a pinch more salt or pepper if needed. Set aside.

Pick any thick stems off the watercress and pop the tender shoots and leaves in a bowl. Trim the roots and top 3cm off the spring onion. Finely slice it on the diagonal, both the green and white parts. Keep a pinch of the green parts to one side and add the rest to the watercress.

Trim the courgette and use a vegetable peeler to peel thin ribbons off the courgette. Peel down to the seeded core, then finely slice the core. Add it all to the watercress.

Juice half the lemon into a small bowl and add 1 tsp olive oil and a pinch of salt and pepper. Whisk together to make a sharp dressing and add to the watercress. Toss to mix. Set aside.

Sprinkle 2 tbsp flour onto a plate and season with salt and pepper. Dip the plaice fillets in the flour, coating both sides.

Put the frying pan back on a medium heat. Warm for 2 mins, then add 2 tsp oil and the plaice fillets. Fry for 2-3 mins, then carefully turn over and fry for another 2-3 mins to cook through. They will be white and flake easily when pressed with a fork.

Slide the plaice fillets onto 2 warm plates and scatter over the remaining spring onion greens. Heap the salad up next to them. Spoon half the pesto over the fillets and serve with the rest of the lemon sliced into wedges for squeezing.