Is this agony??? This is really your problem and I can tell you,
its your character problem.
I take it you are Malay or India, therefore too bad, there is
absolutely no escape. The world does not revolve around you
only.
The food your family cooks is not just to serve you and your taste.
If you don't like, don't eat. You have the choice to just eat the
things you like and leave the onions alone. No one took a gun to
your head and demand you eat onions.
Don't complain cause you propably don't contribute money to the
groceries so that would mean you are free loading off others and
being ungrateful at the same time (it is not a parent's imperative
duty to take care of you - there are families who sell their kids
for money - be grateful yours is taking good care of you).
If you don't like the food, you can always offer to cook for your
family for a month and see how it is like to cook for everyone and
only cook the things you like to eat. Or you can also buy-back or
treat your family to food that you everyday. Then tell them, next
time do a couple of this kind of dishes so that everyone can
enjoy.
If you cannot do any of those, then don't complain. If you don't
give money to the family, don't complain. If you don't prepare food
for the family 365 days a year, don't complain.