First up, if you’re using wooden skewers, soak some in cold water for 10 minutes, so they don't burn when you put them on the BBQ later.
Finely grate the zest of 1 lemon into a large bowl, then squeeze in its juice. Peel the garlic and pound into a rough paste in a pestle and mortar with a pinch of sea salt and black pepper. Tear in half of the parsley leaves, smash together, then add to the bowl with 1 tablespoon of oil.
Pull the heads off the prawns and peel off the shells, leaving the tails intact. Run the tip of your knife down their backs and pull out the vein to butterfly them. Toss the prawns in the marinade, then cover and pop in the fridge for 30 minutes.
Take a bit of pride in skewering up the prawns, don’t pack it on too tightly.
Cook the skewers on the barbecue for about 3 minutes on each side, or until th prawns are pink, then serve.