Do you like rare wine and delicious snacks? Do you like drinking perfectly balanced cocktails in a beautiful setting? If yes, then come on down. Bentley's new and improved bar is ready to provide.

The two-hatted restaurant reopened last week after a fortnight's closure to replace an air conditioning system in the 160-year-old building once home to The Sydney Morning Herald. Co-owners Brent Savage (executive chef) and Nick Hildebrandt (sommelier and wine diviner) also used this time to refresh the dining room and fix a few things that had been irking them since opening at the site in 2013.

The biggest item on that list was the bar. "It was one of those restaurant bars that didn't really have its own identity," said Hildebrandt. Longtime Bentley creative collaborator Pascale Gomes-McNabb has reworked the space and golly, it's a nice place to sit – sexy and sophisticated with light and shadows in all the right places.

A glass balustrade separating the elevated dining room and ground level bar has been covered with a floral dark green mural to create a more intimate space and while also hiding the Bally loafers of restaurant diners. Waxed grey leather banquettes are a delight to sink into and look terrific next to handsome brass table tops.

In collaboration with head chef Aiden Stevens, Savage has created all-new menus for the dining room and bar. A couple of full-menu items cameo among the bar snacks (next time, king prawns with guanciale, koshihikari rice and sea herbs) but you're here for oysters and bread. Specifically, fruity Sydney rocks ($5) from Merimbula and house-made rye with black sesame butter ($4). As an added oyster bonus, south-coast angasis ($10) are lifted with the salty-sweet pop of finger lime and scampi caviar.

Barbecued kingfish collar ($18) is sticky with rich white meat that slides off the clavicle and loves a swipe through smoked yoghurt. It's plated with pickled and grilled cucumber and with a side of hand-cut chips ($14), you have a top-notch light lunch.

Fish sandwiches at posh bars usually involve white bread, a finger of something crumbed and fried, watercress and maybe a dollop of caviar. Savage says bollocks to that. Watercress still makes an appearance on his fish sanger, but here it's crowning half a wholemeal bread roll that's heavy with toothfish and padron pepper-spiked mayo. It's all a bit Scandinavian and a bargain at $16.  

Whether or not a glass of Jean-Francois Ganevat "Chamois du Paradis" 2013 is a bargain at $40 is a matter of more personal opinion. It probably depends on your appreciation of cult Jura winemakers obsessed with terroir and making chardonnay full of life and intensity.

The new Bentley wine list is full of crackers like this – natural wonders from importer Andrew Guard, Keller riesling, Adelaide Hills funksters and Hildebrandt rarities; some from his personal cellar, many sourced on voyages of European discovery. The by-the-glass selection is brilliant and features (at the time of writing) 15 whites, 16 reds and four bottles under the banner of "rose, orange and oxidative". Enjoy.

Cocktails are impressive, too. Check the "homage to the negroni" (Aperol, genever, vermouth and $20) and the Number Seven ($22) where the sweet richness of Zacapa rum anchors oloroso sherry, Angostura bitters and yellow Chartreuse. The Bentley team is mad for Chartreuse – ask co-manager Glen Goodwin to talk you through the liqueur range next time you see him

Bentley's bar was already excellent before the refresh, however Savage and Hildebrandt know how important it is for a restaurant to evolve, especially a contemporary Australian one in the CBD. Change before customers tell you to. With this latest redesign, Bentley has established sure footing to provide after-work martinis and oysters for many years to come.

If you only drink one thing… Jean-Francois Ganevat "Chamois du Paradis" 2013 ($40/$230).

If you only eat one thing… toothfish sandwich with padron peppers and watercress ($16).