Mennula, 10 Charlotte Street, London W1

When I told my friend we would be meeting at a Sicilian restaurant, he made the obvious gag: "I'll be disappointed if there isn't a gun taped to the back of the cistern."

Mennula on Charlotte Street is about as far as you can get from the family-style Italian restaurant in The Godfather where Michael Corleone shoots Virgil Sollozzo and Captain McCluskey. It's in an L-shaped room that feels as though it has been squeezed into a thin, narrow strip by the larger buildings on either side. There are few round tables here – not enough room – just a series of banquettes upholstered with purple cushions. With its modular furniture and plain, white walls, it's more like the set of a Stanley Kubrick movie than one of Francis Ford Coppola's.

The owner is Santino Busciglio and he makes no apologies for the modest interior. "I didn't want to saddle myself with huge overheads," he says. "All I ever wanted was a nice little restaurant I could call my own." Mennula can accommodate about 40 covers and was three-quarters full when I visited, which suggests the chef-patron has the business model about right. Not bad for a Tuesday lunchtime.

Busciglio was born in Agrigento in Sicily, but moved to Bolton when he was a boy. After a stint with the A-Z group at Rosmarino, Alloro and Zafferano, he ended up languishing in the kitchen of a hotel off the Euston Road. He first started thinking about opening his own place four years ago, but it wasn't until this site in Fitzrovia became available that he made the leap. It was formerly the home of Passione, Gennaro Contaldo's restaurant. "I've looked at quite a few premises over the years and this place just leapt out at me," he says. "You know the right one when you see it."

There may be nothing particularly Sicilian about the décor of Mennula, but the menu has the smack of authenticity. The à la carte menu is divided into four sections, beginning with antipasti, followed by zuppa, pasta e riso, then secondi di pesce, carne e selvaggina (fish, meat and game) and, finally, dolci. Prices are on the high side and if four courses feels a little extravagant, there's a set menu offering two for £17.50 or three for £19.50.

My companion – a political fixer – opts to start with squid accompanied by potato sauce, peppers, capers and tapenade, while I cannot resist the in-season white Alba truffle grated over tagliatelle. Admittedly, this adds £25 to the bill and customers are supposed to be limited to five grams of this ambrosia, but the head waiter is happy to keep grating until I tell him to stop. Both first courses are a great success, particularly the squid.

For my main course, I have calf's liver served on a little mound of mashed potato and accompanied by spinach, onion marmalade and speck, while my friend has pork belly with polenta, black cabbage and apple chutney. The calf's liver is perfectly cooked and full of rich, earthy flavours, but the presentation on the plate is a little too fussy, making the quantity appear smaller than it is. Again, my companion is more than happy with his choice, claiming it is well worth suspending his diet for.

As our second courses are being cleared, Busciglio emerges from the kitchen and starts making the rounds of his lunchtime customers. We're both pretty stuffed at this point, but the affable chef insists we try some of his deserts – and not because he wants to maximise his takings. He's just very proud of his food.

I end up with the Sicilian cassata – a layered sponge with chocolate, ricotta and candied fruits – while my friend has the cannoli filled with ricotta, prompting him to quote The Godfather again: "Leave the gun, take the cannoli." The cannoli is the undoubted star here. Busciglio returned to Sicily aged 16 and spent two years living with his grandmother, the village baker, who evidently taught him a thing or two. The pastry is crisp with a slightly burnt flavour that acts as a lovely counterpoint to the sweetness of the ricotta.

There's nothing particularly flashy about Mennula; the lion's share of the work has gone into getting the food right, rather than "the concept". It won't win any prizes and I can't see it ever becoming a destination restaurant. But if you're after simple Sicilian food, lovingly prepared by a talented chef, this is the place to come.

15/20

Scores: 1-9 stay home and cook, 10-11 needs help, 12 ok, 13 pleasant enough, 14 good, 15 very good, 16 capable of greatness, 17 special, can't wait to go back, 18 highly honourable, 19 unique and memorable, 20 as good as it gets

Mennula, 10 Charlotte Street, London W1, tel: 020 7636 2833. Mon-Fri, lunch and dinner. Sat, dinner. About £100 for two, including wine and service

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