It is almost 25 years since I first tasted oysters, but I can still remember my first impression of this slippery fruit of the sea, and what it was like trying to swallow one.

It was difficult just letting it slip over without chewing, but when I eventually managed it, I really began to appreciate them.

My first oyster experience was with wild oysters, and I have never taken to the farmed variety or ‘rock’ oysters as they are known. The texture is completely different and much softer. Once or twice a year, I get amazing, enormous oysters from west Cork that are about 60 years old.

Native oysters are expensive, and work out at around €24 a dozen. They are available for purchase whenever there is an ‘r’ in the month – that is, from September to April. They come from the Atlantic coast – Oranmore, Galway -w here an oyster festival is held every September to launch the season. The shell is harder, much flatter and more difficult to open, but this can be achieved with an oyster knife (prising them open with any other type of utensil can be dangerous).

Pacific, farmed or rock oysters are available all year around. They cost about €6 less per dozen than native oysters and the shell is much easier to open. When buying oysters, ask the fishmonger how old they are. It is always best to buy them with the seaweed, which keeps them fresh. They should be tightly closed and, if the shell appears to be open, discard it. When you open the oyster, release the muscle from the shell and turn it around. They taste great with a pinch of lemon juice.

The best way to eat oysters is the simplest – open, add a splash of juice and knock them back with a glass of Guinness – but at Thornton’s restaurant, my favourite way to prepare them is with champagne and caviar.

Ingredients (for four people)

24 native oysters

100g shallot puree

200ml champagne sauce

50ml of champagne

8g caviar

50g fresh seaweed

4 chervil leaves

Method

1. Open the oysters. Discard the upper shell.

Strain the juice and mix with the champagne.

Place the oysters in the juice. Cover and place in the fridge.

Shallot puree. Ingredients

10 peeled large shallots

25ml of cream

5g unsalted butter

50ml of still water

Sea salt

Fresh-milled pepper

Method

1. Roughly chop the shallots. Heat a pot, melt the butter, add the shallots and cook for ten minutes without colouring. Season with sea salt and fresh-milled pepper.

2. Add the water and continue cooking until nearly evaporated. Add the cream and cook until the cream reduces by three quarters.

3. Remove from the heat and place into a blender for three minutes to puree. Remove and return to the heat for one minute. Remove, taste and correct seasoning. Keep warm for further use.

Champagne sauce. Ingredients

1 shallot, diced

1 sprig dill

1/2 bay leaf

150ml fish stock

50ml dry white wine

100ml champagne

5ml olive oil

Oyster juice

50ml double cream

Fresh-milled white pepper

Method

1. Heat a pot and add the olive oil. Add the diced shallots and sautee for two minutes without colouring.

2. Wash and roughly chop the dill. Add it and the bay leaf to the pot. Add the dry white wine until it reduces by three quarters. Add half the champagne and reduce over medium heat. Add the fish stock, reduce by half, then add the oyster juice and the cream. Season with milled pepper. Reduce by half again. Add the remainder of the champagne and bring to the boil for one minute.

3. Remove the sauce from the heat and pass through a fine strainer. Return to the heat and blend it with a hand blender for a minute or so. This helps to add air to the sauce.

To assemble the oyster

1. Place the seaweed into a large bowl which will give the dish an ocean aroma. Warm the oyster shells and space them evenly on the seaweed.

2. Place the oysters and champagne in a pot on a low heat for two minutes. Do not heat above 50 degrees C.

3. Heat the shallot puree and add to the oyster shell. Remove the oysters from the liquid and place on top of the shallot puree.

4. Coat the oysters with the champagne sauce. Place the caviar on top, garnish with a chervil leaf and serve. A glass of champagne is a good accompaniment.

Kevin Thornton is a Michelin-starred chef and owner of Thornton’s Restaurant on St Stephen’s Green in Dublin.