It is five in the morning as we pat silently across the sodden sands of a Cornish beach. We are hunting for sloe-backed mussels. Not the fastest of prey perhaps but the tide will allow us only a 15-minute window of opportunity before swallowing up our supper.

Led by Katy Davidson, chair of Slow Food Cornwall, we are learning that armed with just a bucket and a net, the beach can be our larder. Waiting patiently at the edge of the sand, finally the sea sweeps away from the rocks to reveal a surface jagged with a thousand mussels.

We climb across, tearing off shells by the handful. Suddenly the French term fruits de mer” makes sense; the clusters of shellfish as abundant as blackberries on an autumn hedge and just as easy to pick.

For, paradoxically, some of the most expensively chichi and rarefied items on British menus — the lobsters, the mussels, the crabs garnished with rock samphire — are some of the most abundant on our beaches. But few of us tend to exploit this, perhaps misguidedly believing that such an activity requires large amounts of expertise or equipment.

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This couldn’t be farther from the truth. While foraging for mushrooms can be gastronomic Russian roulette (are those porcini or poisonous?), foraging for seafood is incredibly simple. If something looks like a mussel, that’s because it is a mussel. “It’s extremely easy for even total novices to get a good haul,” says Katy.

Within a few minutes our dripping bag brims. We already have more than we could possibly eat, but I pillage on, gluttonously. Suddenly I am aware that my feet are soaking. The path to the beach has almost disappeared as the seawaters, their own sustainability sentry, rise again.

“Foraging really is an extremely responsible way to get your seafood,” says Katy as we splash through the sea. “It’s very hard to take too much just using your hands.”

The rising tide spurs us on. Katy intends our search to culminate in a seafront barbecue and we have other fish to find. The next course demands crabs, shrimp, cockles, sea beet and rock samphire. These can be gathered only at low tide from the nearby Gannel Estuary.

Our first targets are the Victorian- sounding cockles. These lie just beneath the surface of the estuary bed and can be found only by feel so we crouch down, scratching at the sand with our nails. Suddenly Katy finds one. Creamy brown and fatly round, it looks like a Guylian chocolate. Encouraged, I scratch faster. Moments later I too strike cockle gold.

The cockle, less excited to be found than I am to find it, spits seawater at me. “Ah, they do that,” says Katy, pleased to see one in action. I look at the cockle sourly: a small line of flesh protrudes from the lips of its shell. It looks for all the world as if it is poking its tongue out at me. I feel a surge of anthropomorphic pity and let it drop back into the water.

After the cockles come some greens; salty rock samphire, curling sea beet and fat ribbons of seaweed. Next we tackle the crabs. These prefer deeper water, so we take our bucket and net downstream. Higher up, the estuary is typical du Maurier; snaking and bosky.

Here at its mouth the sand is so white and the water so blue that it seems almost Mediterranean. We weight our net with mackerel and let it down. Nothing. A family of crabs is visible on the seabed but they seem selfishly keen to avoid capture.

A pleasantly Gerald Durrell-ish half hour passes as we watch them squabble, scuttle and parry. At last one approaches our net. It sidles towards it; pauses. Sidles around it; pauses. Then, finally, wonderfully it sidles into it. Victory! We whip the net up. The barbecue can begin.

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