The Soho version of Bistro du Vin burger, pictured at the top of this post, was an abomination. It arrived as you see it, with a wide crack extending from one side to the other. My initial guess was that a chef had cut the burger open to check it for doneness and broke the fat patty in half, spilling its juices. But the cooking process might have had something to do with its fragility. I finished the job with a steak knife, slicing the burger in two to analyse the damage. What a horror! The burger was impossible to pick up and eat, not that you’d want to. Its meat was hard, mealy and dry – nothing like the crumbly, juicy version on St John Street. It was seasoned with whole peppercorns, not the ideal texture for a burger, and nothing about it tasted right. I dropped the mostly uneaten burger onto its serving board and surrendered.

The hostess came by to ask me what I thought of the burger and I told her. She summoned Keith Shearer, the executive chef of MWB Group Holdings, which operates the restaurants at all Bistro du Vin and Malmaison locations as well as pubs like London’s Fox & Anchor.  Shearer explained he’d been forced to respond to the very real dangers of serving rare or even medium rare burgers. With steaks the exposed surface area of the meat gets seared and bad bacteria gets killed. But when beef is minced any surface contamination gets dispersed throughout the interior. If the burger is cooked medium-rare, as most Bistro du Vin diners want it, the internal temperatures are not sufficiently high to kill all bacteria.

Shearer’s solution is to fry cuts of beef before they are minced, ostensibly killing any bad stuff on the surface before it can be pushed to the interior. The burger is essentially cooked twice, a grave risk to good taste if not good health.

Shearer attributed the peppercorns in the mince and the deep crack in the burger to greenness – that of the young chef who prepared my burger. The restaurant only opened last week. The executive chef offered to prepare me a replacement himself, medium-rare. He raced to the kitchen and returned with a burger 12 minutes later. A photo of the dismal result appears below.

Delivered on a wood chopping board with a groove for a cone of golden frites, the BdV burger is a chargrilled sensation bearing the mark, literally, of the best burger application of a Josper grill in London. A medium-rare arrives charred and crumbly on the surface yet juicy and deep pink throughout the interior. There is none of that inside-out shading from pink to brown, rare to well done. This is beef you want cooked one way all the way through: as ordered. The bacon rashers surrender easily to the chew and the mild chilli dressing, collected for dipping in a copper mini-casserole, is a keeper.

The brioche bun, spritzed with olive oil and toasted on the griddle, holds up remarkably well. It keeps the drippings off your hands from above and below if not from the left, right, front and back.

That’s where the planning issue comes in. Architecturally this burger doesn’t sit all that well on its layered salad cushion of tomato, red onion and round lettuce hanging way out the sides. It needs a hedge trimmer. The expert panelists on Gardeners’ Question Time would not approve.

Even so, the Bistro du Vin already qualifies as the 8th best burger in London. With revisions to the blueprint to improve landscaping and prevent toppling the BdV burger v2.0 is certain to move up the charts and better justify its aggressive price of £14.50.

As you might expect there are tables at Bistro du Vin. These are of little interest to me. From adult highchairs at the bar you can see all the action in the open kitchen. When the chef opens the door to the blazing Josper Grill to load more burgers and steaks you can practically feel the heat.

38-42 St John Street, EC1, 020 7490 9230