I saw these giant prawns at the Borough Markets in London and had to try. They are the same ones as in my userpic.
1. Mix butter, oil, chilli, lime zest, salt and pepper in a bowl
2. Cut the prawn in half lengthwise and remove the crap. Try to keep the coral (the gunky bits in the head) cos it tastes good
3. Brush the butter mix on the prawn and grill until done
I had crusty toasted bread and a squeeze of fresh lime with this, but it also works with a dipping sauce of fresh lime juice, salt and cracked black pepper.