In a small saucepan coated very lightly with oil, saute the kaffir, chile, ginger and onions. Stir until soft and season. Deglaze with fish sauce and completely reduce. Add cream and coconut milk and reduce by 50 percent. Check for seasoning. Strain and set aside. In a saute pan coated with oil, saute the leeks until soft and add the cream and lime juice. Check for seasoning. Add the oysters and poach for only 2 minutes, until just warm. Place the shells on a plate of coarse salt and fill with warm oysters topped off with the leek cream.