Slice through the back shells of the prawns and devein them, leaving the tails (and heads) intact. If you are more adept (than me), devein them by inserting a needle into the tail end and gently pull the vein out that way.
Heat a heavy bottom pan over medium high heat.
Toss the prawns with the salt.
Dry roast them in the pan, a few minutes on each side, until each side is pink and the middle part is barely cooked through.
Serve immediately with a dipping sauce of your choice.
I am sure you could just grill them too, but I tend to not have coals around for my grill. This is the way our household has been doing them for ages...