As I eagerly await the start of the game season, there is still time to think about another of my favourite genres of food: seafood. Having been chef in charge of the fish section in three top London establishments, I have acquired some knowledge of the subject.

Shellfish, in particular, are something a lot of cooks find difficulty with. Understanding the differences and observing a few simple rules can overcome this.

There are two groups: crustaceans and molluscs. The first are those with jointed shells, such as crabs, lobsters and prawns, and the latter are those with hinged shells, such as oysters, scallops and mussels.

Freshness is the key, as well as traceability. I am not keen on the notion of collecting mussels from the seashore, unless the area is completely safe from contamination. Shellfish bought from reputable suppliers will have been through an acknowledged cleansing process. Most shellfish are best bought live, and then cooked at the earliest opportunity.

Mussels and oysters should traditionally only be eaten when there is an 'r' in the month, but varieties brought in from the continent are now safely available for most of the year.

Oysters fall into two main categories: 'native' and 'rock' oysters, often called Portuguese oysters. The native, mostly from Whitstable or Belon, lay their eggs inside the shells during the summer months. Rock oysters lay theirs outside, which is why these are available all year round.

Here is a classic crustacean recipe, simplified: Lobster Thermidor.

Lobster thermidor

Ingredients (Serves four)

2 cooked lobsters, 750g each

50g unsalted butter

50g finely chopped shallots

100ml dry white wine

1 heaped tbsp fresh tarragon

2 teaspoons of Dijon mustard

50g grated Parmesan cheese

50g grated Gruyère Cheese

2 egg yolks

Method 1) To remove the meat from the shell, lay the lobster on a flat surface (preferably a large board) and insert the knife into the cross on the back of the shell. Pressing firmly down, split the crustacean in two. Remove and discard the track which runs down the middle of the tail, and take out the meat. Next, carefully crack open the claws and the knuckles, with a mallet or rolling pin, and remove the meat with a pick, or skewer. Retain the shells.

2) Cook the shallots in the butter, without colouring, until soft. Add the wine and reduce by half, then add the cream, and simmer for 3-4 minutes. Add the mustard and tarragon, and season to taste.

3) Mix in the yolks, and then add the diced lobster meat.

4) Spoon the mixture into the shells, and sprinkle with the grated cheese, mixed together.

5) Place under a hot grill for about five minutes until golden brown and serve at once.