Q. Why eat doughnuts on Chanukah?
Because the Chanukah miracle involved oil, the characteristic foods are fried.
Doughnuts (ponchkes) and potato pancakes (latkes) vie with each other in popularity despite the fact that they are fattening (indeed the lighthearted and lightheaded might find serious food for thought in the question of whether flattening the latkes makes them less fattening).
The Hebrew for “doughnuts” is sufganiyot, from safag, “to absorb”. Literally this is because they absorb the oil they are fried in – but metaphorically doughnut recipes are an absorbing subject.