Opening oysters requires practice and can be dangerous, as the knife can slip. To prevent injury, hold the oyster with a thick cloth to protect your hand
Insert a knife with a rigid, sharp, short blade (preferably an oyster knife) into the hinge of the shell and twist the knife to prise open the shell
Remove the oyster from the shell and wash the shell
Mix the tomato, ginger, coriander, onion and sugar in a bowl and season
Spoon into the empty oyster shells and place a fresh oyster on top of each shell
For the horseradish mayonnaise
Mix the mayonnaise with half the horseradish and the lemon juice. Season
Spoon a little sauce over each oyster and sprinkle with the remaining horseradish