Bob’s Lobster, Unit 71, St Thomas Street, London SE1 3QX (020 7407 7099). Snacks and small plates £3.50-£11; large plates £12-£22; seafood tower £40; desserts £6; wines from £25

In the movies that carry her name, the fictional Bridget Jones lives a short, tear-stained, snot-smeared stumble from the real location of Bob’s Lobster, tucked into one of the spaces beneath the newly renovated London Bridge station. It’s a tidy fit because this would be exactly the kind of place Bridget would want to visit to eat away the pain of a calamitous break-up. In particular, she should order the fries with mussel and bacon chowder, because they will make everything better. I say “with” the chowder, because that’s how the menu describes it; “submerged in” is closer to the mark.

Behold: a deep, soothing bowl of a wine and cream-based chowder, bobbing with Ford Cortina-orange mussels, into which has been dumped a whole serving of rather good chips. Pile a few more pert mussels on top, along with a bacon crumb and finely diced green herbs and spring onions to make it look like all the vital food groups have been covered, and there you have it: solace in a bowl. It’s a pescatarian take on Lancashire’s classic chips and gravy. The ones on the top are crisp; the ones beneath are a yielding soggy mess of cream and seafood and potato and profundity. Lean over and shovel it in, until your cheeks are slicked with soup and the bad thoughts have gone away.

It’s an outrageous and joyous menu item – the word “dish” might be pushing it – which sums up the full-frontal assault of the food here. The cooking laughs in the face of the mostly American dishes it names on the menu. The succotash isn’t quite a succotash; the shrimp and grits would make a native of the state of Georgia frown. None of that matters, because most of it is very good. It’s called Bob’s Lobster because it grew out of the initials of Bedales of Borough, the wine bar back near the market (which, as it happens, occupies the site of what was the Greek restaurant in the original Bridget Jones movie). It helps that the founder is called Roberto Dann; there’s a bona fide Bob involved.

Dann was looking to diversify from their wine and small plates offering, so he imported a vintage red-and-white VW camper van and started flogging lobster rolls out of it at Borough Market. The polished camper van now sits in the high-ceilinged space they’ve taken over in the red-brick undercarriage of London Bridge station. It’s just opposite the Vinegar Yard street food market that opened a couple of months ago. What was, until very recently, a deserted and scuffed Bermondsey drag is now, on a warm Thursday evening, full of bustle and shout and the merry clink of glass on glass.

Here at Bob’s there’s a bar knocking out foaming pisco sours. They have an oyster happy hour late every Monday to Friday afternoon with bivalves at a quid each. For £8 they will make you a fishfinger sandwich, or fried chicken with anchovy salsa verde, while £40 gets you a “seafood tower” of oysters and prawns, salmon tartare, scallops and tuna tostada. For an extra £20 they’ll chuck the lobster tail on, too.

We start with tuna tacos, which arrive tucked into a deep groove chiselled down a polished plank of wood, so it looks like a taco luge. It’s a significant amount of engineering to keep these elegant pockets of sashimi-grade tuna, wasabi-boosted guacamole, chipotle-flavoured cream and deep-fried wonton shells fully contained. There are four of them for £9. Each one is three or four satisfying mouthfuls of quality raw fish, acidity, crunch and spice. Unlike the chowder-splashed fries, eating these feels like an act of virtue.

As does the succotash, which should probably come inside inverted commas. It keeps to the essentials, being a mixture of sweetcorn and podded broad beans. The addition of courgettes, fresh mint and, in particular, crumbled feta, leads it off towards the southern Mediterranean rather than the southern US. More familiar is the lobster and crayfish roll in a soft, sweet and toasted brioche bun: a bit of claw meat, a lot of crayfish (to keep the price below £20), a bed of crunchy coleslaw and all is right with the world.

Shrimp and grits includes both those things: a large portion of big, shell-on shrimps and a sticky puddle of ground cornmeal grits, shown a good time in the open kitchen. The thick, gooey cornmeal has been spiked with jalapeños and bacon (if in doubt, add bacon. As we know, this is a fine code by which to live.) The prawns have been sautéed and the pan deglazed with bourbon. The boozy, buttery mess has then been poured all over the dish. It’s not subtle, but it is good.

Only the lobster bisque doesn’t quite work and that, I think, is because it cleaves too closely to old-school New Orleans cooking. In Louisiana they’ll tell you theirs is the only truly classical culinary tradition in the US. Partly this is because they use lots of fancy French words. Menus are splattered with things like “boudin” and “beignet”; it sounds classier than sausages and doughnuts. Meanwhile, classic recipes for gumbos and étouffées have at their base a sauce aggressively thickened with flour. The lobster bisque here is one of those flour-thickened sauces, trying to pass itself off as something rather better-heeled. It’s generous on the lobster and I’ll never pass up a deep-fried crouton, but the soup is just a whisper off setting into a jelly.

Oh well. Find relief in a dark, gooey chocolate brownie topped with a whorl of thick cream, made happy by the application of children’s party sprinkles. Any leftover brioche buns from today’s stock for lobster rolls will turn up here, in tomorrow’s bread and butter pudding. It’s studded with sultanas and bathed in vanilla custard. If this all feels a little heavy, do as we did and mark this moment by ordering the pisco sours. Or perhaps, don’t.

None of this is subtle. None of this is poised. But it’s big on flavours and it’s huge on joy. All of it is overseen by a young staff who appear to give a damn. For most of the time Bob’s Lobster is a very appealing restaurant. But when emotional times are hard, and nice things are needed, I think it can also become something else. I think it can serve as a vital emergency service.

News bites

For another take on the food of the American south try Plaquemine Lock, a pub in London’s Islington specialising in Cajun and Creole cooking, from Jacob Kenedy of the Italian restaurant Bocca di Lupo. Many of the classics are here, from Cajun cracklins through shrimp with grits to fried green tomatoes and Jambalaya, all at reasonable prices. It is a labour of love by Kenedy, who has family from Louisiana (plaqlock.com).

The onward march of great pie continues. Piecaramba, the vintage comic shop and pie wranglers who started in Winchester, are opening their third outlet in Brighton’s South Lanes. The names are as punning as ever – the Woolverine for a lamb and redcurrant jelly pie, the Chick Norris, for a chicken in curry sauce number – but they’re always good and cheerily priced, plus there are extensive non-meat options (piecaramba.co.uk)

The team behind Franco Manca, the sourdough pizza company which started in Brixton market in 2008 and now has dozens of outlets across the UK, is to launch a pasta restaurant. Strozzapreti will be part of the 26-strong trader line-up at the food-based Seven Dials Market, inside the 19th Century Thomas Neal’s Warehouse in London’s Covent Garden.

Jay Rayner will be appearing in a special Guardian Live event at London’s Cadogan Hall on 9 September. In My Last Supper, the show accompanying his soon-to-be-published book of the same name, Jay examines our fascination with last meals and tells the story of his own. Click here for tickets.

Email Jay at jay.rayner@observer.co.uk or follow him on Twitter @jayrayner1