Winter gone, sun is out and Dublin has decided to party. At least that’s how it feels in Bow Lane on Aungier Street tonight. The building is throbbing with music and speckled with people who woke up milk-bottle white this morning and tried to dial their skin tone up to swarthy.

The 40th birthday at the long, large table next to us, which has just gone (phew) is making way for a 21st according to the bouquet of helium balloons in the middle. But it’s fine. They’re a lovely crowd, all ages enjoying each other’s company over dinner and drinks.

In the ladies, there’s talk of a cake in the shape of a Leinster jersey for another table. Down the back, small candles are being blown out. Everybody seems to be out on a big night. I’m here because the bar, which is a sister to the Whitefriar Grill, has a new menu. On a night this busy in what seems to be the city’s birthday HQ it will be a tough ask for a kitchen to shine. But here goes.

We got through the door of Bow Lane after passing a towering doorman who asked us if we had a reservation. This is a new thing on me but then a Saturday night on the town is not my natural habitat. In the low-ceilinged bar there’s a smell of woodsmoke from the fancy cocktail things that are happening. A DJ is playing music.

Bow Lane is divided into bar on one side and restaurant on the other. The zones are pretty fluid. The music from the bar is a cross-border presence throughout the night. “There’s a reason I don’t go out on a Saturday night,” my friend semaphores from across the table. We may have to make like millennials and talk by text.

But enough grumping – this menu sounds deadly. And at the start it is. Nduja oysters, three of them come in their shells with the spreadable Italian salami melted over the oysters like piggy jam. There are some excellent sourdough soldiers to scoop up these gloriously messy mouthfuls, although we could have done with more in the regiment rather than the few last men standing.

I get the dish of the night: lengths of perfect charred octopus as pink as an Irish sun-worshipper with a luscious length of soft chorizo sausage. There’s tang from a pickled half-artichoke heart and vegetable brine from a caper puree. It’s a plate that nails it, exactly what I want to eat with a crisp cold glass of hoppy craft beer.

And then it all goes south. In freefall fashion. It’s as if the chefs have gone for cocktails and handed the kitchen to hard-working but clueless kitchen porters.

My cauliflower steak won’t convert any meat-lovers. Watery florets of cauliflower are arranged in a steak shape on the plate peppered with Young Buck blue cheese and dotted with poached grapes. When you strip away the artful plating it is, sadly, just bad cauliflower cheese with some sour green grapes.

The other main of lamb is better – juicy slices of roast rump. It comes with clams. The clams are nice but oddly out of place. We wonder is it a rhyming idea, lamb and clam? Next is Spam maybe?

Underneath the clams there’s a squid-ink butterbean mush that looks like tile grout and is about as pleasant in texture, tasting of mealy underseasoned beans. A side of broccoli has spent too long in its cooking water. Mousseline potatoes are good.

Desserts swerve back on to the good track, presumably made earlier in the day before half of Dublin decided to descend on this old building.

We share a chocolate pave, a slab of good spoon-sticking bitter-sweet chocolate silkiness with peanut-butter ice cream arranged on a skid-mark of chocolate painted on the plate with a brush.

I’m cheered by Bow Lane despite the meal of two halves. They’re making a proper effort to feed people well.

The first plates show how the Venn diagram of food and booze can cross deliciously.

So stick to the starters, skip the middle page and go straight to dessert. Treat Bow Lane like a tapas bar and I think you’ll be well-pleased.

Dinner for two with a glass of wine and a glass of beer came to €86.