Preparation Cook greens in a 6- to 8-quart pot of boiling salted water until ribs are tender, 4 to 5 minutes, then drain in a colander. Rinse under cold water to stop cooking and drain well, gently pressing out excess water. Heat oil in a 12-inch heavy skillet over moderate heat until hot but not smoking, then cook garlic, stirring, until pale golden, about 30 seconds. Increase heat to moderately high, then add greens, red pepper flakes, and salt and sauté, stirring, until liquid greens give off is evaporated, about 4 minutes.
Preparation Cook greens in a 6- to 8-quart pot of boiling salted water until ribs are tender, 4 to 5 minutes, then drain in a colander. Rinse under cold water to stop cooking and drain well, gently pressing out excess water. Heat oil in a 12-inch heavy skillet over moderate heat until hot but not smoking, then cook garlic, stirring, until pale golden, about 30 seconds. Increase heat to moderately high, then add greens, red pepper flakes, and salt and sauté, stirring, until liquid greens give off is evaporated, about 4 minutes.