you could ask your any male relative on your dad side, us being a patrilineal society. they could give you the dishes served per the customs of your lineage.
generally, the vegetables used are pre-european ie vaazhakkai, chenai and what not. also the spice used is the pepper (milagu). no chllies or potatos or any 'english' vegetables.
if you are in a situation where you are unable to cook, an acceptable substitute to food, is just rice/raw vazhakkai to the priest.
all in all, it is a matter of faith. for after it is a sombre poignant ceremony done as much out of love as out of duty.
God Bless.