Combine the lime juice, fish sauce, sesame oil, rice wine vinegar, vegetable oil, sugar and lime leaf in a small bowl. Set aside for at least 20 minutes to allow the lime leaf to infuse the dressing.
Remove the leaf and whisk to emulsify. Taste and, if necessary, add a little extra vinegar or sugar for balance.
Arrange the oysters on a bed of rock salt, then either serve the dressing on the side or spoon a little over each oyster before serving. Top with a red chilli and coriander (if using) just before serving.