This is a good supper: uplifting, light, energizing and head-clearing. Add other vegetables – spinach, broccoli, thin slices of mushroom, edamame beans – to the pak choi, or use them instead of it. Minced turkey also works if you can’t get minced chicken. And yes, minced chicken is not leftovers, I do realize that. But this dish earns its place in this chapter because it uses stock, made from the remains of your Sunday roast.