Cover your hand with a tea towel and lay the oyster flat on your hand. Use the tip of the oyster knife and insert it into the “hinge” and gently twist the knife to pry the shell open. Cut the muscle from the shell by sliding the knife along the inside of the shell. Fresh oysters should smell of sea and saltwater. Discard any shell that smells bad. Carefully remove any small pieces of shell and place the oyster in coarse salt or crumpled tin foil. Mix the chilli, lemon grass, lime juice, lime zest and shallot. Top the oysters with the mixture and a little coriander.