Stir-Fried Greens

Nutritionists exhort us to add turnip, beet, dandelion, and mustard greens, kale, spinach, broccoli rabe, and Swiss chard to our weekly diet because they are so healthy. I love them though, not for their salubrious effect, but their lusty flavor. Unfortunately the more exotic types of greens are not that easy to find, but I never substitute the frozen variety (except for spinach) for the fresh, because frozen greens are wilted and taste bitter.