Having confusion regarding shivratri fast?

Hi guys, tomorrow is shivratri .when i was in delhi that time i obsorve fast whole day and used to eat after 8 o' clock something which is made by kuutu ka aata and aalu ki sabji. but now im in kerala here kuttu ka aata is not available . some people says that we cant have onion, salt, turmeric aur garlic on shivrati. is it true? if it so pls tell me wht shud i eat after opening the fast arond 9 o clock.