Barbecued oysters with bacon and tamarind sauce

Ingredients

• 230 gm bacon rashers (we like double-smoked)
• 80 gm tamarind pulp, soaked in ¾ cup hot water for 30 minutes
• 160 gm light palm sugar, crushed
• 1 tbsp fish sauce
• 5 small red chillies, crushed in a mortar and pestle
• 24 unopened oysters
• 3 golden shallots, thinly sliced, to serve
• ½ bunch Thai basil leaves, to serve
• To serve: lime halves