In my years of cooking I've learned to ignore, or actively flee, the advice to "use only the freshest ingredients." It's impractical, wasteful and often harmful. This is an opportunity to pass along a favorite passage from my beloved Tassajara Cookbook*:

Nowadays we are often advised to eat the best, to enjoy the freshest. And we shop for only the finest. I guess I'm in another school. My Zen teacher, Suzuki Roshi, would buy the worst-looking vegetables. "Who will use them if I don't?" he would ask. The grocery clerk would try to dissuade him, "Wouldn't you like something fresher?"  When his wife joined him here in America from Japan, she wouldn't let him go shopping anymore.

It's an ancient Zen tradition, not wasting anything, including leftovers: we understand that the way you treat one thing is the way you treat everything, so study carefully how to use the moment before discarding it.