For the prawns, place the butterflied prawns in a bowl. Grate the ginger into a clean tea towel or cloth and twist to squeeze the juice onto the prawns. Discard the ginger flesh. Add the lime juice and zest, salt and freshly ground black pepper, garlic and chilli and leave to marinate for five minutes.
Heat a little vegetable oil in a griddle pan, add the marinated prawns and chargrill for 3-4 minutes, or until the prawns have turned pink and are completely cooked through. Transfer to a bowl, add the coconut and stir well. Add the spinach and stir.
For the caramelised onion, in a separate frying pan, heat one tablespoon of vegetable oil, add the onion and cook over a gentle heat for eight minutes, or until the onion has caramelised.
To serve, place the prawns on a serving plate, top with the caramelised onions and scatter with pine nuts. Garnish with the fresh coriander leaves.