A traditional Bengali meal is not served all at once. Courses arrive in a set order that begins with something bitter and ends with something sweet, and the order is treated as part of the food.
The bitter opening resets the palate
The meal starts with a bitter preparation, often built on bitter gourd or bitter greens, served with plain rice in a small quantity.
Bitterness is the most persistent of the basic tastes and the one that most strongly primes the palate. Coming first, it makes everything after it register as fuller.
Placed later it would flatten the dishes around it, which is precisely why it occupies a position nothing else competes for.
The middle builds intensity in steps
Lentils and simple vegetables follow, then fried items, then fish or richer dishes, with each stage more assertive than the one before.
Building this way means no dish is eaten against a palate already saturated by something stronger, so mild preparations get eaten while they can still be tasted.
It also spreads a meal over time rather than presenting everything simultaneously, which changes how much of each item is actually eaten.
A sour course sits before the sweet
Toward the end comes a sour preparation, frequently a thin fruit-based dish, tart and lightly sweetened rather than heavily spiced.
Acid cuts the accumulated richness of the fish and fried courses, which is the same job a squeeze of citrus does elsewhere but given its own position.
It also functions as a bridge: sweeter than what came before, sharper than what follows, so the transition to dessert is not abrupt.
The sweet ending is structural, not optional
Bengal's dairy sweets close the meal, usually followed by plain curd, and their position is fixed rather than a matter of whether anyone wants dessert.
Because the sweets are made from drained curd, they are light and wet rather than dense, which is what allows them to be eaten after a full meal.
This is not incidental. The regional sweet tradition and the meal structure developed alongside each other, and each explains the shape of the other.
The sequence survives outside Bengal in compressed form
Served in a restaurant or at a busy table, the same courses often appear together on a plate, arranged in the order they are meant to be eaten.
The arrangement on the rim of a thali carries the sequence visually, which is why the placement of items is consistent rather than decorative.
A diner who eats around the plate in that order gets most of the effect, even where the timing of separate courses has been lost.