If you felt like being a jerk, you could argue that this poignant Indian drama looks to have been constructed with the overseas market in mind. It makes sure to include second-unit shots of Mumbai at its most exotic. The film has much to do with conspicuously delicious local food. The largely epistolary romance takes cues from that in Ernst Lubitsch's timeless The Shop Around the Corner (itself the basis for You've Got Mail ).

So what? The Lunchbox remains one of those films that gives words like "tender" and "touching" a good name. You would need to be some sort of monster to resist its charms.

The picture's central misunderstanding adds further anthropological detail to the depiction of Mumbai. Ila (Nimrat Kaur), a modestly unhappy young woman, makes lunch for her husband each morning and dispatches it to his workplace via the deliverymen known as dabbawallahs. Somehow or other (the switch is never explained) Ila's food ends up going to a widowed middle-aged insurance worker named Saajan (Irrfan Khan).

Ila’s husband barely registers the confusion, but Saajan is quite taken with the splendid curries and daals. He and Ila begin exchanging letters via the unaware dabbawallahs. When Ila gets wind that her husband might be having an affair, she considers running away with her remote correspondent.

The film is rich with gentle humour that reveals truths about the two likable lead characters. Ila is endlessly patient with a chattering “Auntie” who, never seen, offers advice from the flat upstairs. Saajan is initially wretched to a young apprentice, but, softened by his new relationship, ends up easing the young man’s path.

What really makes the film soar, however, are the performances. Kaur eventually breaks like an injured bird while Khan, as inward and careful in his movements as ever, confirms his status as one of the very greatest actors in world cinema. The Lunchbox doesn't quite deliver him the meaty role he deserves, but that is sure to some soon.