Food: Big pink

Probably the best salmon recipe in the world; The fillet from the wild fish had a clarity of taste that transported me to the very bottom of the ocean

Many, many years ago, salmon was so plentiful in the river Thames that the resident polar bear at the Tower of London was let loose on a rope to catch its supper. Nowadays, though, I wouldn't trust the finest fisherman I know to bring me my supper. Wild salmon in the rivers is scarce to non-existent.

Still, with the arrival of June and the promise of sunshine, salmon and strawberries, I was sent scuttling for the familiarity of a favourite recipe: Jane Grigson's Salmon in Pastry with Herb Sauce, which she, in turn, borrowed from the Hole in the Wall in Bath.

Its glory is in the inclusion of ginger in syrup and currants that sit between two thick fish fillets, basted as they cook with buttery juices - all tightly enclosed in a crisp exterior of very short and crumbly pastry - the salmon "en croute" to end them all.

I have it earmarked as "fantastic recipe" in a stained and battered paperback of Grigson's Fish Cookery. I ate it first, many years back, at the hands of a friend who was a wonderful cook. And he would only make it using wild fish.

This was also my intention, until I found my fishmonger selling wild salmon at pounds 12 a pound, meaning the fish for the pie would be pounds 50, and that before you started to think of niceties like wine. And this was "cut price", my fishmonger informed me - it should have been more like pounds 15, compared to pounds 6 a pound for farmed. I settled, reluctantly, for the latter.

With such a compromise in place, I felt determined to prove to myself that farmed and wild are not so very different, and acquired a fillet of each. These, I then char-grilled for lunch with a green salad.

The fillet from the wild fish was enviably thick in the middle, inches of it, tapering away towards the outside. Once seared, the golden, crusty bits on the surface gave way to large, meaty flakes of pale pink flesh that were firm and textured. Its taste had a clarity that transported me to the very bottom of the ocean.

The farmed salmon, which came from the same shop and I am confident was a very fine example of its kind, sported the same delicious crusty patches on the outside, and I would have been hard-pushed to comment on the difference in flavour. What varied was the texture, which was softer and more oily; the flakes did not achieve the same firmness or hold their shape.

But I didn't finish my lunch woefully thinking I had made the wrong choice. The better specimens among farmed salmon are perfectly good for spreading with a flavoured butter and baking in shortcrust pastry.

Perhaps more to the point, it is, arguably, a waste of wild salmon to treat it thus. As a commodity that requires some respect, the purist's approach, to poach or grill it, is about as good a treatment as you can give it.

As to the price: while standing in my fishmonger in Notting Hill Gate and fretting over the decision of what to buy, the manager, Michael Lear, put me straight on why the price of wild salmon drops so radically as the season progresses. I had always put this down to availability and how plentiful the various spring, summer and autumn runs were.

But not so. So much salmon is netted out at sea that the runs in the rivers, during the last couple of years, have been virtually indistinguishable. It is the other "season" that is to blame - Royal Ascot, Wimbledon and Henley - for which some 65 per cent of the harvest is reserved.

The remaining 35 per cent is scarce enough to fetch ridiculous prices. It's not until after Wimbledon, when about 90 per cent of fish are available on the open market, that the price sinks to a realistic level for "salmon in pastry". For four or five glorious weeks, it costs little more than farmed. So, if you want to make this recipe with wild salmon, it's worth waiting until the tennis is over.

Salmon in pastry with herb sauce, serves 6

I have toned down the original sauce which contained quantities of butter, cream and egg yolks more popular in the Seventies than today.

Pastry:

275g/10oz plain flour, sifted

pinch each of salt and sugar

175g/6oz unsalted butter, diced

1 medium egg, beaten

1 egg yolk beaten with 1tbsp double cream

Filling:

1.125kg/212lb salmon fillet, skinned and pin bones removed

sea salt, black pepper

75g/3oz unsalted butter, softened

2 knobs preserved ginger, chopped

1tbsp currants

milk

Sauce:

2 shallots, peeled and chopped

6tbsp chopped parsley, 2 tsp chopped tarragon, 2tbsp chopped chervil (optional)

25g/1oz unsalted butter

1tsp plain flour

275ml/12pt double cream

1tsp Dijon mustard

150ml/5fl oz strong fish stock

lemon juice

To make the pastry, place the flour, salt, sugar and butter in the bowl of a food processor and reduce to crumbs. Bring together with the egg. Wrap in cling film and chill for 1 hour.

Preheat the oven to 200C (fan oven)/220C (electric oven)/425F/Gas 7. The salmon should be in two thick fillets, season these with salt and pepper on both sides. Mix the butter, ginger and currants together in a bowl, and use two-thirds of it to sandwich the fillets together. Spread the rest on top.

Roll out the pastry on a floured surface, turn the salmon out on top of it and bring the edges together so it is completely enclosed - you can moisten them with a little milk. Cut away surplus pastry, turn the salmon dumpling onto a foil-lined baking sheet so the pastry edges are underneath. You can roll out the pastry trimmings to make a decoration for the salmon. Brush the whole thing with egg yolk and cream, and bake for 30 minutes.

To make the sauce: sweat the shallots and herbs in the butter until they are soft. Stir in the flour, the cream, mustard and seasoning, and cook over a very gentle heat for 5 minutes, stirring. Gradually add the fish stock, bring back to a simmer and cook for another 5 minutes. Add lemon juice to taste and adjust seasoning.

Transfer the salmon to a hot dish, lifting it up by the foil beneath. Ease this away, and serve straight away with the sauce in a separate bowl.