Julie Vu knew where to find the right baguette for her bánh mì sandwiches at City Càphê, the Vietnamese luncheonette she was planning to open this month in the City of London. She just wasn’t sure she could find it within 100 miles of Ironmonger Lane.

The baguette she grew acquainted with on forays to Vietnamese sandwich shops in the Belleville quarter of Paris was crackly but not hard, its thin crust giving way to an airy interior without the chewy, open-holed texture of traditional French baguettes. In London she sampled dozens of prototypes but despaired of sourcing anything exceptable until, voilà, she thinks she has it.

I wasn’t invited to Friday’s staff sampling of bánh mì in advance of the official opening on Monday (7 September). I just happened to be in the area, scouting burgermonday possibilities, when I spotted the City Càphê from afar. It’s amazing how my distance vision improves when the subject relates to coffee (càphê is Vietnamese for café). I entered the adorable shop and saw that Julie (left) and her friend Fiona Duong (center) were offering samples of their bánh mì.

The baguette, as viewed in this detail of sandwich cross section, looked bready to the eye, but its airiness was immediately apparent upon first bite. The interior compressed into the fillings as the flaky shell shattered in my mouth. Yum. Yes, I think she has it.

The three varieties of bánh mì I tried were already good, if a little plain, and likely to get better. With her baguette in hand Julie is prepared to think more about fillings and proportions as well as delve into more philosophical questions, such as: to mayo or not to mayo? Authentic or not I am fine with a brush of mayo on the baguette, as long as it’s just a coating and not the main ingredient. For mayonnaise sandwiches in which chicken, beef, pork, tuna and egg are merely accessories we already have Pret.

City Càphê – 17 Ironmonger Lane, London EC2V 8EY

Likewise, discriminating young Londoners who, when within three Chardonnays of sober, wouldn’t be caught dead with a Tesco tomato in their organic jute carrier bags can be seen stuffing their reddened faces with questionable kebabs from an Upper Street shop that recycles its moulded and fully cooked meat, unrefrigerated and unprotected, for hours at a time.

At the risk of sounding like a drunken pensioner, things aren’t what they used to be, at least not for me.

In my younger & foodish days, when I got smashed with much greater frequency and far more dedication than I do now, I always tried to finish off a night of binge drinking by stuffing my face with trash food of the highest quality. As a student in Montreal I looked forward to being booted from my local, Taverne Henri Richard, so my drinking buddies and I could rush off to Schwartz’s for its incomparable smoked meat, Le Chalet for succulent rotisserie chicken, an all-night Polish social club for handmade potato pierogi, Arahova Souvlaki for juice-dripping gyro sandwiches or St-Viateur for sesame bagels fresh and hot from a wood-burning brick oven. From these experiences grew a straight C student – and eventually a professional food critic.

Back in my native New York we would hobble if necessary to Katz’s Deli for world-class pastrami, the Market Diner for a copious burger deluxe, Florent for steak frites, Junior’s for its famous cheesecake, Wo Hop for the greasiest subterranean chow fun noodles in Chinatown or, on one particular Saturday night bender, three of the aforementioned.

Living in Paris years later we would crawl on our knees to L’As du Falafel for its amazing spécial, Au Pied du Cochon for gelatinous pig’s trotters and golden onion soup gratinée or the last Vietnamese open in Belleville for a crusty banh mi.

In fairness to London’s late-night, liquored-up foragers, their city is lacking in 24-hour eateries worthy of their loyalty. If London imagines itself a – or even the – gastronomic capital it will have to improve in this category.

To this end I have a suggestion to underground, pop-up restaurateurs, existing as well as aspiring: Why don’t you serve high-quality impulse food in your flat on weekends from midnight to 4 am? Think of all the advantages: You wouldn’t be competing with licensed restaurants. You’d be performing a public service while enhancing London’s status as a great dining city. Were your soufflés to fall it’s unlikely that anyone would notice, much less give you grief. And given the likelihood that someone will purge the food you spent hours preparing you would not be expected to put out fancy linens.