Remove the stems from the kale and chop the leaves coarsely. Wash and drain well, but do not dry. Heat a large sauté pan, add ¼ cup olive oil and enoungh kale to cover the bottom of the pan, and cook over high heat while stirring to rotate the leaves. Add more kale as the leaves wilt. When all of the kale has been added, season with salt, cover, and reduce the heat to medium. Cook, stirring occasionally; the cooking time will depend on the maturity of the kale. Young kale will be tender after 4 or 5 minutes. It may be necessary to add a splash of water if the leaves begin to scorch. When the leaves are tender, remove the lid and allow any excess water to cook away. Push the kale to one side of the pan and add an extra drizzle of olive oil, the garlic, and a pinch of red pepper flakes to the bare spot. Just as you smell the aroma of the garlic, stir to combine it with the kale. Turn off the heat, add a splash of vinegar, and correct the seasoning with salt and pepper as necessary. Serve warm or room temperature.