My aunt bought some houmous thinking it was vegan when it wasn't. How do I tell her she made a mistake without upsetting her?
The other day, I was at a family dinner. My aunt didn't mind making it a vegan meal.
She bought houmous thinking it was vegan. My little sister pointed out (to me, privately) that it wasn't vegan because there was some white cheese inside (she knew because she had helped to transfer the houmous from the box into a nicer container. I didn't ask her if she actually did read the ingredient list but she wouldn't have known there was "white cheese" in it otherwise. I wasn't very surprised because I have seen houmous with cheese in it in the past).
Later during the meal, my cousin asked me if I had checked that the chips were vegan because, sometimes, there are eggs in it. I hadn't (I didn't know they put eggs in some chips), my little sister ran to see if they were, they were.
My aunt got mad at my cousin (her son) and said that she had checked the chips and that she also had checked the houmous and there weren't any eggs in it so both were vegan.
I didn't say anything to my aunt (because I didn't want to upset her further). I just double checked with my sister that the houmous wasn't vegan (she was sure that there was cheese in it, I believed her).
My aunt bought the houmous thinking it was vegan (because it had no eggs in it) but it wasn't, as there was cheese in it. Now she might make the same mistake in the future. I don't want this to happen but I also don't want to hurt my aunt (she is a very sensitive person).
What I tried
Nothing. When she told my cousin she had checked for eggs, it was a very bad timing to tell her that the houmous was, in fact, not vegan because of the cheese.
How to communicate to my aunt that she made an honest mistake when buying the food for this family meal, without upsetting her?
Notes and clarifications
I'm the only vegan in my family but my other cousin (my aunt's daughter), who wasn't there that day, is vegetarian.
Even though my little sister is not a vegan nor a vegetarian, she is very supportive of me and will always be on my side when it comes to veganism.
My aunt knows the difference between vegan and vegetarian (she had put vegan cheese on the lasagna and she buys me rice milk when I stay for the night). I think she just didn't notice the cheese in the ingredient list (I, myself, had the same problem a few time when I start becoming vegan).
I'm 23 and my sister is 17.
I never saw the ingredients list but I trust my sister.
This happened yesterday
The houmous was only a part of the appetizer, not the main course (so I had other stuff to eat).