Mashed Fava Beans with Preserved Mustard Greens

KATHY: The first time Grandma Fang placed a plate of mashed fava beans on the dinner table (which, incidentally, was right in front of a TV blasting Chinese soap operas—the TV was always on at Grandma Fang’s house), I remember thinking to myself, Wow, how did she make these mashed potatoes green?!

In my world as a kid, the mashed potatoes from KFC—you know, the ones served in a Styrofoam cup with a plastic lid—were the ultimate treat, somethi