Why Grill an Oyster?

Raw oysters with a squeeze of lemon and a slice of brown bread are one of the great pleasures of the British coast, but they are not the only way. Grilling an oyster transforms it. Over high heat the liquor trapped in the shell begins to bubble, the meat tightens and its edges ruffle and curl, and the briny juices reduce into something deeper and more savoury. Add garlic butter in the final minute and it melts down into that liquor, mingling with it to make a sauce you would happily eat with a spoon.

It is also one of the fastest starters in British cooking. Four to five minutes on a hot grill, a handful of parsley, some good bread, and you have something that tastes like a day out at the seaside. Natives from Whitstable and West Mersea, rocks from Loch Fyne, Cornwall or Jersey — all of them take to the grill beautifully. Cooking them this way is not a way of disguising an indifferent oyster; it is simply a different expression of a very good one.

Buying British Shellfish: What to Look For

Two oysters dominate British fishmongers. Native oysters (Ostrea edulis) are flat-shelled, round and richly flavoured, traditionally in season from September to April — the old "avoid months without an R" rule. Pacific or rock oysters (Crassostrea gigas) have a deep, cupped shell and are grown all around our coast. For grilling, the rock oyster is the better choice: that cupped shell holds the butter and the liquor instead of tipping it into the coals.

• Buy them live. Shells should be closed, or close slowly when you tap them. Discard any that gape and will not shut.
• They should smell of clean sea, never of fish or ammonia.
• Ask your fishmonger when and where they were harvested — most decent ones will tell you the bed.
• Store in the fridge at around 4°C, cupped side down, under a damp cloth. Never sealed in a plastic bag, and never in fresh water.
• Use within two or three days. Six per person makes a generous starter; a dozen is a main course with bread and salad.

Shucking Without Tears

You need three things: a proper oyster knife with a short, stiff blade, a protective glove or a folded tea towel, and a sturdy surface. Scrub the shells under cold running water before you start.

Hold the oyster cupped side down in the towel, hinge facing you. Push the tip of the knife into the hinge, then twist rather than lever to pop it. Slide the blade along the inside of the flat top shell to cut the adductor muscle, lift the lid away, then slide the blade under the meat in the cupped shell to release it there too. Leave the oyster sitting in its own liquor — that liquid is the base of your sauce, so do not tip it out. Check each one for fragments of shell, and chill them on crushed ice while you make the butter.

Garlic and Herb Butter: Simple and Generous

Restraint matters more than complexity here. Take 100g of softened salted butter — or unsalted with a good pinch of flaky sea salt — and mash it with the following.

• One or two cloves of garlic, crushed to a paste with a pinch of salt. More than that and the garlic overwhelms the oyster.
• A small bunch of flat-leaf parsley, finely chopped, stalks and all.
• A squeeze of lemon juice and a little grated zest.
• Optional, and all the better for it: a finely chopped shallot, a splash of dry vermouth or Pernod, a pinch of cayenne or smoked paprika.

Roll the butter into a log in cling film and chill it, then slice it into discs — one per oyster. If you are short of time, simply spoon a little over each one. The butter can be made a day ahead and kept in the fridge.

On the Grill: Heat, Timing and Judgement

Get your barbecue, ridged grill pan or oven grill properly hot before the oysters go anywhere near it. Arrange the half shells cupped side down so the liquor stays put, and sit them on a bed of coarse rock salt if you have it — it steadies them and stops them sliding about. A baking tray of salt also works under an oven grill.

Cook for three to five minutes. You are looking for the liquor to bubble vigorously and the edge of the oyster to curl and ruffle. The centre should still be tender, just opaque at the rim. Add the butter disc in the last minute of cooking, not at the start, so the garlic does not catch and turn bitter. If your grill has a lid, close it briefly to help the butter melt. Six to eight minutes and you have rubber — so stay with them.

Expect a little crackling and spitting from the shells, and be careful of the steam when you move them. Tongs and a steady hand are all you need.

Serving, and a Few Good Variations

Serve them the moment they come off the heat, on a plate with the salt still clinging to the shells, with lemon wedges, crusty bread and a sharp green salad. Eat them within the hour. A dry Muscadet, a Chablis, a crisp British sparkling wine or a dry cider all work well; a stout is surprisingly good with the grilled, smoky ones.

Once you have the technique, play with the butter. Chilli, lime and a little chopped chorizo is excellent. Smoked paprika with a drop of sherry is deeply savoury. A crumb of cooked bacon and chives turns them into something heartier still. Whatever you choose, keep the flavours few and let the oyster — salty, sweet, faintly metallic, entirely of the sea — remain the point of the dish.