In 2014, Nuno Mendes, a chef from Lisbon by way of Wolfgang Puck’s kitchens and his own Viajante in Bethnal Green, opened a restaurant at the Chiltern Firehouse hotel. This is a redbrick Edwardian castle in Marylebone, which used to be a fire station, but no longer is. This restaurant was skilful: both blessed and cursed. I thought it was Gatsby’s house, inhabited by people looking for something they would never find because it does not exist: self-acceptance through the incitement of jealousy, which is the emotional purpose of being rich.

People went for the empty pleasure of being seen at the Chiltern Firehouse because the prime minister David Cameron, among others, came for Caesar salad with chicken skin, which was presumed to be interesting like he was. Skin aside, the food was less important than the performative presence of what calls itself society inuring itself to its own hubris, and rot. This restaurant was gaudy, but it did not make sense. Mendes is a thoroughbred, and a donkey was required.

This was a shame, because Mendes, who looks like a benevolent wizard, is one of the great chefs of the age and we are lucky that he works in London. He is a maverick, and imaginative, but unlike others he does not forget the diner, who can take only so much maverick imagination. The only exceptional things about seafood-flavoured ice cream are its facetiousness, and the credulousness – and decadence – of those willing to eat it.

Now Mendes has done something for himself and his oppressed food. He has fled from Hello!magazine and opened a restaurant called Lisboeta on Charlotte Street, which is too close to other restaurants to be as fashionable as the Chiltern Firehouse, which, spiritually at least, requires its own country estate, and possibly its own decade. He wants to bring ‘the ebb and flow of Lisbon life’ to London as a gift as it declines into authoritarianism and tarmac. Lisboeta means ‘person from Lisbon’ – is he lonely? Did the Chiltern Firehouse make him lonely?

Lisboeta is on three floors in the bright blue Victorian house that used to be L’Etoile. The exterior is painted dark blue: Lisboeta is in golden letters over the door, and, in its transient way – all restaurants are transient, there is nothing more transient than a restaurant – it deserves it. There are seats outside for those willing to face the air pollution which drifts through central London like black pollen. Inside, on the ground floor, there is a long bar and a kitchen, and tiny tables by the window into which we fold ourselves, when we understand that our arses are now unequal to the bar stools. It’s a glum rite of passage.

The floors are marble or wood; the walls are exposed brick; the banquettes are pale brown; plants live on shelves; there are paintings of Lisbon on the walls. It is, said one reviewer, ‘a Pinterest interiors board come to life’, which makes me question how often he leaves his bed. The staff are charming in the way that only people who like people can be.

The food is divided into ‘small plates’ and ‘larger pots and platters’, which is irritating but here any copy-writing is forgivable. We eat glorious, slender leg of black pork from the Alejento; superb sheep’s cheese from Serra de Arrábida; a deep, rich slow-cooked lamb shoulder with red wine, spring greens and bread stew; a bright tomato salad with orange and coriander; later, a perfectly balanced and presented biscuit cake with butter-cream, coffee and ice cream. This is food as a charm: Mendes’s best restaurant yet.