This is how to eat, all summer long. A plate of beautiful tomatoes with fresh oregano, another of prosciutto San Daniele, and Baker Bleu's sourdough baguette with cultured butter. Some fresh cheese perhaps. A green salad. A cold beer. That's it, done.

Next Door is next door to Margaret, the Double Bay restaurant that is, in many ways, the culmination of Neil Perry's long and storied career.

It's the meat in the sandwich between Margaret, which colonises the entire corner of Bay Street and Guilfoyle Avenue, and cult bakery Baker Bleu, a joint venture between Perry and bakers Michael and Mia Russell.

The long narrow site was the very likeable Roxy's, and now opens for early morning takeaway coffees (handy when you're in the queue at the bakery), and all-day dining from noon, four days a week.

It's a casual, come-as-you-are spot, which in Double Bay usually means activewear from Anine Bing and Varley.

In the evening, dolled-up patrons pop by for spicy martinis before dining next door, but at Saturday lunch, everyone but me appears to have jogged here.

Everyone also orders the burger. It's what you do, apparently. For $30, Perry's American cheeseburger comes with a tasty 200-gram Coppertree Farm beef patty (a mix of brisket and chuck), rose mayo (spiked with chilli and tomato sauce), onion and pickles in a not-too-squishy bun; a proper two-handed job.

The bloke at the table next to me munches his way quietly through one, looks at his empty plate, orders another one, and munches his way through that, too. People stare.

In body weight, it's the equivalent of the David Blackmore salt beef Reuben sandwich ($32), another two-hander that sees toasted rye stacked with oozy Swiss cheese, mustard, tangy pickles, and 11 (yes, I counted them) slices of cured brisket. It's hard to find good salt beef, and this is good.

There's a special synergy that occurs when a restaurant colludes with a bakery, because the breads can be designed fit-for-purpose; something Californian chef Thomas Keller successfully templated in 2003 with his twinned Bouchon Bistro and Bouchon Bakery.

Another diner draws my attention to Neil Perry himself clearing tables, stacking plates and taking drink orders. "What's that about?" he says, bewildered. Perry takes a few shifts at Next Door when he's not on the pass at Margaret or filling ficelles with ham for Baker Bleu. "Staff shortage," I reply. "You get who you can these days."

The tight kitchen team is headed by Sam Bourke, who worked his way up from scratch at Rockpool with head chef Corey Costelloe, then Rosetta with Richard Purdue (now head chef of Margaret), and is one to watch.

Clearly, he has absorbed Perry's cardinal rules of cooking fish, and a fillet of herb-crusted coral trout ($49) from North Queensland's Ben Collison is pearlescent inside.

It's a credit to this fine fish that it stands up to the intensity of Perry's classic slow-cooked roast tomato sauce. Add fries ($9) and a glass of Clarence Pinot Blanc ($14/$65), a fresh, full-bodied Tassie white with a lovely bite of acid, and that's it, done.

Next Door is the sort of place you find more easily in Europe, where you can either go high or low or both.

A burger, or Kinkawooka mussels mariniere ($29) served in a winey, leek-infused broth that practically screams for more bread.

A tin of anchovies, or steak a la minute ($39), the tender fillet cut horizontally in half and flash-cooked, drowning in curry-spiced Cafe de Paris butter.

End on a crusty, laminated xuxos de crema ($10) sweet Catalan pastry, and that's it, done.

Spin-off brands often become bigger than the mothership because you get the same quality for less – less time, less money, less fuss. Watch out, Mr Perry. The offering at Next Door is so right for now that your restaurant, Margaret, might end up being called Next Door instead.

The low-down

Next Door

Drinks A clipped Margaret wine list with about 20 wines by the glass, plus the Margaret Martini (with choice of five gins), seasonal cocktails and craft beers

Vibe Bar, pitstop, diner and waiting room, Double Bay-style

Go-to dish Herb-crusted coral trout, $49