GREENS
MANY COOKS THINK THEY CAN TREAT ALL leafy greens the same way, even though some are delicate enough for salads while others seem as tough as shoe leather. After cleaning, stemming, and cooking more than a hundred pounds of leafy greens, we found that they fell into two categories, each of which is handled quite differently.
Spinach, beet greens, and Swiss chard are tender and rich in moisture. They require no additional liquid during cooking. They taste of the earth and minerals but are rather delicate. Kale as well as mustard, turnip, and collard greens are tougher and require the addition of some liquid as they cook. Their flavor is very assertive, even peppery in cases, and can be overwhelming.
We tested boiling, steaming, and sautéing tender greens. Boiling produced the most brilliantly colored greens, but they were also very mushy and bland. The water cooked out all their flavor and texture. Steamed greens were less mushy, but clearly these tender greens did not need any liquid. Damp greens that were tossed in a hot oil (which could be flavored with aromatics and spices) wilted in just two or three minutes in a covered pan. Once wilted, we found it best to remove the lid so the liquid in pan would evaporate. This method has the advantage of flavoring the greens as they cook.
Tougher greens don't have enough moisture to be wilted in a hot pan; they scorch before they wilt. Steaming these greens produces a better texture but does nothing to tame their bitter flavor. Tough greens benefit from cooking in some water, which will wash away some of their harsh notes.
We tested boiling two pounds of greens in an abundant quantity of salted water and what might be called shallow-blanching in just two quarts of salted water. We found that cooking the greens in lots of water diluted their flavor too much. Shallow blanching removes enough bitterness to make these assertive greens palatable, but not so much as to rob them of their character. Blanched greens should be drained and then briefly cooked with seasonings.