Heat 1 tablespoon oil in a Dutch oven over medium heat. Add kale and cook, tossing with two large spoons, until bright green, about 1 minute. Add water, reduce heat to medium-low, cover and cook, stirring occasionally, until the kale is tender, 12 to 15 minutes. Push kale to one side, add the remaining 1 teaspoon oil to the empty side and cook garlic and crushed red pepper in it until fragrant, 30 seconds to 1 minute. Remove from the heat. Stir in vinegar to taste and salt.
