Spread the salt over the bottom of a 10 inch gratin dish or other shallow ovenproof dish. Place the prawns in one layer directly on the salt, pushing them down slightly to partially bury them in the salt. Remove the baking dish from the oven. Place the aioli in a small bowl and nestle it into the center of the baking dish, with the prawns on the salt around it. Bring it to the table as is.
Guests can use their fingers to remove the shells and dip the prawns into the aioli.
Have a bowl for the shells and finger bowls for guests. This site is best viewed with Internet Explorer or Netscape Navigator .