The Walnut Tree Inn, Abergavenny

It's never too late to visit The Walnut Tree. If you think you're beyond being impressed, arrive hungry and think again

What can I say about a restaurant that has been there for 38 years? That for much of that time represented a source of hope and wonder, like a samizdat pamphlet in benighted times, for eating out in Britain. That was the impossibly hard-to-please Elizabeth David's favourite restaurant. That even when, it was generally held, enlightenment had spread elsewhere, still put others to shame with its commitment to the most inspired, brilliant, robust cooking. Could The Walnut Tree be as good as everyone said?

As well as the shame I felt for never having been (like a literary editor who hasn't read a word of Graham Greene), and the anxiety of anticipation – were we hungry enough to do it justice? – there was the fear that I'd left the visit too late.

For if lunch can take on so much significance, imagine the responsibility of taking over the restaurant from Franco and Ann Taruschio. That's what Stephen Terry did earlier this year. When he was one of the most talented, though seemingly restless, chefs working in London, the last meal of his I ate consisted of several tiny courses, with glasses of two-tone mousses appearing in between. It didn't seem to make him a natural successor to someone whose cooking was renowned for being influenced by his native Italy, by a feeling for history and by produce which friendly farmers supplied and gardeners brought to the door. Franco Taruschio came from the Marche region south-east of Tuscany, settled in the Welsh Marches and became woven into the fabric of the region, embroidering dazzling patterns of garlic and parsley, capers and chillies, olive oil and pine nuts on to a background of wild salmon, pigeons, Welsh lamb, leeks, blackberries, damsons raised or picked locally.

Although the menu changed constantly, some of his dishes were legendary: vincisgrassi was an 18th-century lasagne with Parma ham, creamy sauce, Parmesan and white truffles, and Lady Llanover's salt duck, the breasts salted and baked and served with pickled damsons, came from a 19th-century recipe book by a local baroness.

On the side of the Skirrid mountain, The Walnut Tree has few immediate neighbours but became a mecca for bon viveurs in and around Abergavenny and everywhere else. Anyone taking over the restaurant would surely mess with its menu at their peril.

By all accounts the new owners haven't. Terry is in partnership with another London incomer, Francesco Mattioli, who runs front of house as Ann Taruschio did; many of the waitresses are the same. Neighbours I met the night before said the cooking had hardly changed either. We were able to do something we wouldn't have been able to a year ago: book for Sunday lunch. We went with children aged five and three. The restaurant was fine about it. The kids less so. It's a plain place, more dining room than pub, but still bare tables, tough carpet. Just as well.

No concessions are made to eating light. Before our order came slices of a savoury tart, the crumbliest pastry filled with gorgonzola and spinach, pungent and ethereal; a fabulously prescient combination of heaven and earth. There was more pastry and more breadcrumbs to follow; it only mattered because we didn't pace ourselves as well as we should have and it only happened because, distracted by the children's demands – "no, there aren't any nuggets or sausages, try chicken with rice and pasta" – we had ordered inattentively. Let this be a lesson to other novices; go with an enormous appetite, a fattish wallet (the food alone will cost £30) and preferably not with children. But go anyway. It isn't too late.

Crab and saffron tart graded from golden on top to sweetly pink underneath, on pastry almost capable of levitating, came with cucumber slices branded by a grill. Breadcrumbed sweetbreads, were, I think, the pinker lamb's glands rather than the more usual calves', with a piquant caper and shallot sauce.

We couldn't resist helping ourselves to the younger child's tagliolini with Parma ham, courgettes and artichokes, flecked red and green with chilli and parsley. This was probably the least rich of half a dozen pastas such as tortelli with pumpkin with sage, butter and Parmesan or pappardelle with hare sauce. Ours was a starter size; goodness knows how you'd manage a main course afterwards.

Seeing his father's monkfish in breadcrumbs, the older child let out an aggrieved cry of "nuggets". He was bought off with chips, a bowl of the most beautiful golden strips of the longest potatoes he'd ever seen. We had less success persuading them that cime de rape, a bitter, leafy calabrese was a relative of broccoli. Chicken with a pumpkin risotto cake and rocket pleased the five-year old so much we had to distract him to raid his plate. A craving for Sunday roast was far better satisfied by tortino – a cake of sliced potato layered with shoulder of lamb in melting shreds, shot through with rosemary and garlic, with grilled leeks and carrots, and with meat juices, not an add-on jus, that seemed to issue forth from the succulent, salty meat and potato wedge like a spring. Meanwhile the monkfish goujons (which weren't called that), in a caper and lemon and parsley sauce a little too similar to that which came with the sweetbreads, defeated even my usually insatiable co-parent.

We hadn't waited all these years to give up now. Puddings – a shallow dish of peerless crème brûlée with blackberries and, though I've never seen the point of plastering chocolate inside pastry, a tart with a chocolate filling so moussey it made lethally heavy chocolate tarts seem not worth dying for. Coffee came with home-made cantuccini. Phew. What a way to go.

So I am. Even if it is a facsimile of what made The Walnut Tree great, I now know what everyone's been talking about and retire (not necessarily permanently) from reviewing. From next week you'll find Tracey MacLeod and Richard Johnson, the man to whom the reviewer's spoon has passed and whose appetite will be virgin sharp, writing about restaurants in The Independent Magazine. I wish them many meals as joyously good as this one. I'm off to put right one more shameful omission, but won't be reporting back. Can The Ivy be all it's cracked up to be?

The Walnut Tree Inn, Llandewi Skirrid, Abergavenny, Gwent (01873 852797) Tue-Fri lunch 12-3pm, dinner 6.30-11pm, Sat 6.30-11pm, Sun 12-3pm