Shouldn't tell the truth. The consequence of this is that she will use this as an excuse in turn and say: Your cooking is delicious. If you cook it later, I won't cook it either.

Then, this situation needs you to say it euphemistically. It can not only discourage her from cooking, but also help her improve her cooking.

For example, you can tell her that you saw a dish on Tik Tok, which was very delicious. There is a video on it, you can follow it and ask her if she wants to try it!