Prawn stock would be the beginning, it will enhance the flavour of the prawns as well as make it salty.
It's made basically from the shells of the prawns. Fry them gently in olive oil until they are a deep red colour. Add, a small amount of chopped celery/carrot/onion and garlic cloves, salt and pepper and cook for 5 or so minutes until soft, then add a litre of water, bring to the boil and simmer 20 minutes and strain. You'll then have your "stock" for the sauce.
Then cook your prawns in olive oil not for long, add garlic, white wine, reduce the wine then add the prawn stock, some pistachios.
Prior to adding the pistachios, cook them on a flat tray in the oven until crunchy.