People sometimes try to sneak meat and meat products into vegetarians by claiming a recipe is veg when it contains (usually) chicken, fish or meat stock or lard. It is done with malice aforethought, because they lie when you ask, and it will make a long-term veg very sick. I can catch it about 90% of the time by taste before it does any harm. Either way, you lie about what you serve me and you are no friend of mine and if it is a restaurant, I will never eat there again, and will tell everyone I know that the kitchen cannot be trusted. NyaCha's mother was entirely wrong to misrepresent the food. NyaCha has every right to be angry. I am not sure there is a polite way to handle it as I find the offense so egregious. If, say, my ILs tried it (never have, never would, but...) I would never eat food they prepared again, unless it was obviously meat-free, like a green salad. Carrot sticks. Or I brought it.