In the evening, he will ask you what is my favorite food? Just ask him politely, what would you do if I said I was lying to you?
He must be disappointed at this time, and then you take it out on him. Tell him it's wrong to lie, especially between relatives.
Then ask him, did you lie? He will understand your intention.
Remember not to use a heavy tone from beginning to end, but always treat your friends. Otherwise, it will be counterproductive. Lies will get angry when they are exposed.