The classic way to cook collard and turnip greens—especially for those of us who grew up in the South—is to braise them with pork, either smoked ham hock or thick-cut bacon. The flavor of the pork mellows out the greens and gives them a much needed salty boost. The fat makes the leaves tender and silky.
• Our general method for the toughest greens (collards and turnip greens) goes like this: Cook some thick, chopped bacon in a heavy saucepan until the fat is rendered. Add the greens (which we've sliced into ribbons) and cook in the pork fat with plenty of salt and pepper until they are wilted. Add enough chicken stock or water to barely cover the greens, cover the pot, and cook for about half an hour or more, until the greens are soft and an army green color. That's right. We like ours to lose that all-important, vitamin-packed bright green color. We like 'em a little overcooked.
If you are a vegetarian, or just don't want to use pork fat, you can cook your greens in olive oil. But we'd recommend salting heavily and adding stock rather than water for more flavor. Of course, there are myriad variations. Some people add cider vinegar, wine, or onions. Some people boil their greens and then drain them.
Turnip Greens Cooked in Rich Pork Stock, from Bon Appétit
Related: Less Meat, More Flavor: Salt Pork