It's a phrase you hear all the time: "This [stew] [soup] [long-cooked-thing-X] will be even better the next day!" It's an appealing prospect. Most foods are best when they're at their freshest, but a dish you can make in one large batch that doesn't just hold up, but actually improves with time? That's a make-on-Sunday, eat-all-week recipe right there. But is it true? I did some testing to find out.