These greens are tender and almost even sweet from being gently cooked with onion. They're also spicy from a generous dose of ground ginger and black pepper. Hearty greens like kale and collard greens that can stand up to longer cooking times and benefit from soaking up strong flavors work particularly well in this dish. For an extra kick, try using mustard greens or turnips greenstheir sharper flavor works really well here. If you want to use a quicker-cooking green like chard or spinach, simply reduce the cooking time after you add the greens to the pan (don't worry, it's noted when to stop with them in the recipe below). Note that these greens may seem like they're cooked for a long time. They are, in a way. In modern american cooking, greens are often simply wilted and served. Here, they are allowed to do more than just wilt. They're cooked so they release their liquid, which combines with the spices and aromatics to create a flavorful cooking liquid whose deliciousness the greens then simmer and soak in, absorbing all that extra-tasty goodness.