Indian restaurants abroad are increasingly identifying themselves by a single region rather than offering the long undifferentiated menu that defined the trade for decades. Several conditions had to align for that to become viable.
The standard menu became a known quantity
The generic curry house menu succeeded because it was legible to diners who had no reference points. Once a large audience had eaten it repeatedly, its uniformity became a limitation rather than an advantage.
Diners who can already name half a dozen dishes are looking for a reason to choose one restaurant over another, and a shorter, more specific menu answers that question directly.
Restaurants competing on breadth all end up looking alike, whereas a regional focus is a claim no neighbouring competitor can easily copy.
Supply chains had to catch up first
A regional kitchen depends on ingredients the general trade does not stock, from particular rice varieties and dried fish to specific chillies and fresh curry leaves in volume.
Importers began carrying these once enough restaurants existed to sustain the demand, which is a circular problem that resolved gradually as immigrant communities grew in particular cities.
This is why regional restaurants cluster rather than spreading evenly, and why the same concept can be straightforward in one city and impractical an hour away.
Migration changed who is cooking
The earlier restaurant trade drew from a narrow set of origins, which is a large part of why the standard menu looks the way it does.
Later migration has been much broader, bringing cooks whose home food had no representation on that menu and who had little reason to reproduce it.
Opening a restaurant serving their own regional food is both the easier option and the more distinctive one, so the incentive runs in the same direction as the ability.
Shorter menus change the kitchen
A focused menu allows the kitchen to abandon the base gravy system and cook dishes on their own terms, which is what makes regional specificity possible at all.
It also reduces waste and simplifies purchasing, since a small ingredient list is used across the whole menu rather than sitting idle for infrequent orders.
The trade-off is that the restaurant cannot accommodate every request, and it depends on diners accepting a menu that does not include the dishes they might have expected.
What has not changed
The general menu remains dominant by volume, particularly outside large cities, because it serves a broad audience and needs no explanation.
Regional restaurants also tend to add familiar items over time under commercial pressure, which is how the standard menu absorbed most of its contents in the first place.
The direction of travel is towards more specificity available in more places, rather than towards the general menu disappearing.