I groan when those emails arrive: friend of friend coming to Edinburgh, wants to see the sights and taste real Scottish food. Inevitably they want to visit the castle: £19.50 for an adult, £11.50 for a child. I tell them it’s a military museum and you can get the view for free from the esplanade. I prepare them for our tourist trap High Street, where upmarket cashmere shops nowadays display their prices in both Chinese Yen and Sterling. But where shall I tell them to eat?

I can recommend restaurants in the vicinity, but do they count as Scottish? What is Scottish cuisine these days anyway? It’s certainly not the old Taste of Tartan cliché. That died decades ago, although deep-fried haggis balls still beckon to the unwary. For me it’s about ingredients with a sense of place, like North Ronaldsay lamb, or Arbroath smokies, and the manner in which ingredients are produced. Were those razor clams patiently harvested on the beach, for instance, or electro-blasted out the water? The finest Scottish food is like any other nation’s finest food, the antithesis of globalised and mass-produced, unique. And then with immense relief I remember Cannonball, run by Carina and Victor Contini, whose steadfast support for artisan food producers in this country is second to none.

We know to arrive strategically early, which bags us Cannonball’s best table, the one with that bird’s eye panorama of the castle esplanade and entrance. Don’t fret too much if you can’t sit there though, because this is a congenial restaurant throughout. It has those roomy dimensions, and friendly, Edwardian design features from when it was a constructed as a school in 1905. Strategically placed skylight windows create a striking pattern of shadow and light.

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You’re always looked after well at Cannonball. Front of house staff anticipate what you need before the thought firms up in your head; they’re a step ahead. And you’re beautifully served too: heavy cutlery, streamlined glassware, handmade stoneware plates and bowls with a Japanese simplicity about them. I’d pay go to see an exhibition of these ceramics. And what a backdrop this putty-grey speckled one makes for the Ethical Fish Company’s Isle of Mull king scallops, sweet and pearly within their lacy, amber-fried exteriors. This is one of the best treatments of scallops I’ve come across, with its crisps of Jerusalem artichoke, slender, charred baby leeks as if just thinned from the allotment, and enveloping dulse seaweed mayonnaise. The minute we smell the glorious aroma from the twice-baked soufflé we can know that it owes its sumptuous intensity to an extraordinary cheese, in this case, the Errington family’s legendary Lanark Blue. Made from raw ewe’s milk, it is to my mind Scotland’s finest blue cheese. Here’s another ceramic that could feature in a photographic exhibition, a speckled, mottled, gently curving bowl with the puffy, amber-baked soufflé perched on a pea green velvet cushion of confit leeks cream, strewn with a tangle of crispy deep-fried leeks, here and there the odd candied walnut echoing the nutty character of the cheese.

My only gripe with the main courses is that they’re huge, too big for me, and I hate to leave food this good uneaten. “Posh fish and chips” isn’t cheap at £22 but then it’s enough for two, so effectively £11 per head for harbour-fresh, sustainably caught haddock, and a juicy langoustine served with epic chips, fresh pea purée, beetroot Tartare sauce, and a wedge of lemon, most likely Italian, that’s dripping with juice. Lobster Thermidor macaroni cheese? We can’t resist. It’s rich, filling, the pasta provides the scaffolding for a pungent sauce made from aged, unpasteurised Isle of Mull cheddar, cream and brandy that’s studded with fleshy nuggets of lobster meat. £24, but there must be half a lobster in there. We can only manage one dessert between us, marshmallow-light bread and butter pudding made with soft golden raisins soaked in 10-year old Glengoyne malt whisky. It’s dreamy. Tourists will love it, but then so do we.

Cannonball constitutes a haven of Scottish authenticity and good cooking at the heart of the Royal Mile tourist trudge. Thank you, Carina and Victor, for creating a restaurant here that I can honestly recommend.

Cannonball, 356 Castlehill, Edinburgh 0131 225 1550

Food: 9/10

Atmosphere: 9/10

Service: 10/10

Value for money: 9/10