Cook the peas in a large pot of boiling water for 2-3 minutes until just tender, then remove with a slotted spoon and transfer in a bowl with ice and cold water. Drain, pat dry and set a handful of peas aside for garnish.
In a food processor add cooked peas, lemon juice & zest, garlic, pine nuts, basil leaves, olive oil and a generous pinch of sea salt and black pepper. Blend until smooth for about 1 min, scraping down the edges with a spatula half-way through.
Add the pasta and prawns into the pot where you previously cooked the peas. Add 1 tablespoon of salt and allow to cook for about 3-4 mins, until pasta is tender and the prawns are cooked through.
Reserve 50ml of cooking water and drain both pasta and prawns.
Transfer them into a bowl, stir through the pea pesto, reserved peas and a little bit of cooking water for a creamy result. Mix everything well, and add sea salt and black pepper to taste.
Divide the pasta into four plates and serve immediately.