Shake the rinsed greens in a colander to remove the excess liquid, but the leaves don't have to be thoroughly dry.
Heat a large pot over high heat until very hot. Add the olive oil. When the oil is almost smoking, add the garlic and cook for a few seconds until it is light brown. Add a couple of handfuls of greens and toss with tongs, incorporating the garlic so it doesn't burn on the bottom of the pan.
Add the remaining greens all at once, or in batches if your pot isn't large enough to hold it all at once. Toss constantly so the greens wilt evenly. When wilted, season with salt and pepper. Continue cooking over high heat, tossing often, until the excess liquid evaporates.
Turn greens out into a bowl and let it cool to room temperature, then season with vinegar. Serve at room temperature, or refrigerate for up to 2 days and eat cold.
Michael's Notes: The wine vinegar will cause the greens to lose their beautiful green color. You can omit it, but I think it improves their taste.
Recipe courtesy of Michael Chiarello