A dish eaten far from its origin is rarely the same as the version at home. The changes follow a consistent pattern driven by what is available and what sells.
Substitution starts with what cannot be sourced
The first alterations are forced. A specific chilli, cheese, fish or grain may be unobtainable, and the cook replaces it with the nearest local equivalent.
Those substitutions cascade, because changing one component alters the balance and prompts adjustments to seasoning, cooking time and texture elsewhere.
Within a few steps the dish is genuinely different, even though nobody made a decision to change it. Each individual substitution was reasonable on its own.
Equipment shapes technique as much as ingredients do
Dishes developed around a particular heat source, clay vessel or fuel behave differently in a standard commercial kitchen, and the results diverge accordingly.
Cooks compensate with method, often extending cooking times or adding fat to reproduce a texture the original equipment produced directly.
This is why some dishes travel well and others do not. Those depending on a specific heat behaviour are the hardest to reproduce elsewhere.
Local palate selects which version survives
Restaurants adjust towards what their customers return for, so heat, salt, sweetness and richness drift towards local expectations over a few years.
The process is gradual and driven by sales rather than intent, and cooks are frequently unaware how far the recipe has moved.
The version that becomes established in a new place is therefore the one that adapted successfully, not the one that stayed closest to the source.
Migration routes leave a visible trail
Dishes usually travel with people, and the version found in a distant city often reflects the specific region and period those migrants came from.
That can preserve older forms which have since changed at home, so the transplanted version is sometimes closer to the historical dish than the current one.
Tracing which regional variant took root in a given city explains a great deal about the food available there today.
Authenticity is a moving reference point
Because the origin continues to evolve, comparing a transplanted dish against the current home version measures divergence rather than corruption.
Cuisines that appear most traditional have usually absorbed ingredients from elsewhere at some earlier point, which the passage of time has made invisible.
The more useful question is what a version is trying to do, since a dish adapted deliberately and one adapted by accident are different propositions.