Culture
Onam
A harvest festival: pookalam, sadya, and the boat.
When
The Malayalam month of Chingam, usually August or September.
Region
Kerala
Onam is a festival of Kerala's land, not a closed rite of one group. A pookalam of flowers is laid at the door, the sadya is served on a banana leaf, and boats race on the river. The story of Mahabali is told in the house.
If a full sadya cannot be cooked abroad, a line of flowers and one meal eaten together keep Onam alive. A complete menu matters less than the family sitting at one leaf.
This is a general introduction. Sequence, materials, and timing change with family, region, and shakha. Your priest and your own custom have the last word.