Set up a sieve over a bowl and shuck the oysters and their liquor into the sieve and let them drain for at least 15 minutes. Weigh off 100g of the liquor and freeze the remainder for other purposes.

Sauté the leeks in the butter with some pepper until they are softened, but not coloured, add the fennel, stir through and then add the white wine reduction and oyster liquor and reduce rapidly by about one third. Do not add salt oyster liquor and the oysters may be sufficient. Stir through the cream, bring to the boil and then stir in the Pernod and chopped fennel top.

to serve
Crumple foil onto a lipped baking sheet and set the oyster shells level on the foil. Place an oyster in each shell.

Pre heat oven to 200°C
Rewarm the sauce and spoon it over the oysters. To this point can be done in advance but should be left at room temperature.

Place in the oven for 5-10 minutes until the fennel is just bubbling and is lightly coloured. Serve immediately.