In much of Spain, the main cooking greens are spinach, chard, and cabbage, but in Galicia, where Ana is from, grelos are also extremely popular.
The word grelos is usually translated as kale, but in fact grelos produce nabos, a turnip-like root which is eaten separately, while the leaves of grelos most closely resemble those of collard greens. So what are grelos? Just think of them as another leafy green in the cabbage family like kale or collards or turnips, but, like the others, distinct. Outside of Spain (and often even Galicia) grelos are rarely available (I can't even find grelos seed for sale) but collards, turnip greens, and the more tender varieties of kale can be substituted.
By far the best known use of grelos is the caldo gallego. (See my post on vegetarian caldo gallego for a recipe and information). But there are many other ways to prepare grelos. They may be served on their own as a side dish or with salt cod as a main dish. Ana's grandparents used to cook chorizos and potatoes together with grelos.
Almost all of the traditional preparations of grelos involve a long, slow cooking, often with pieces of cured, smoked pork. I must admit that I do enjoy eating grelos cooked this way: there is nothing like a hot cup of rich, smoky caldo (the Galician equivalent of Southern "pot liquor") on a cloudy, drizzly day in Galicia.
Here in the U.S. I usually prepare grelos-like greens in a more modern way, but with a Spanish twist: I quick-cook them with olive oil, garlic, and often pimentón de La Vera, which gives them a rich, smoky flavor, much like that of smoked pork. (See my post on pimentón de La Vera for more information about this spice). Often I will add a splash of vinegar, which transforms them into grelos adobados.
For quick cooked greens, it is extremely important to select greens with young, tender leaves. If you start with huge, mature turnip greens, collards, or the thicker varieties of kale, they will need to cook longer. Luckily small bunches of young, tender green are increasingly available in our local markets.
Here's the recipe
1 small bunch of young, tender greens (kale, collards, or turnip greens)
1/4 cup of olive oil
2 cloves of garlic, chopped
1/4 teaspoon of hot red pepper flakes or 1/2 teaspoon of pimentón de La Vera
a splash of wine vinegar
First wash the greens in several changes of water. Remove the harder, tougher parts of the stem. (With really tender greens, much of the stem can be eaten: it has a nice crunch). Chop the greens very coarsely in ribbons.
In a heavy bottom pot or pan, fry the garlic in the olive oil until fragrant, but not browned. Remove the pan from the heat and let the oil cool some. Add a pinch of salt, the pepper flakes, or the pimentón de La Vera. Stir. Add the chopped greens, stir them until well coated with oil, and return the pot to the burner. It's usually not necessary to add any liquid. The water clinging to the leaves is enough.
Cook the greens on medium, stirring until they wilt. Cover the pot and let them steam on low heat until tender. This usually takes 10 minutes but it may take more or less time, depending on the tenderness of the greens.
When they're done, toss them with a splash of vinegar, if you like.