Remove stems and center ribs from kale. Wash and pat dry. Coarsely chop to measure 24 cups. Bring water to a boil in an 8-quart stockpot. Add kale; cover and cook 3 minutes. Drain well; place kale in a bowl.

Melt butter in a small skillet over medium-high heat; cook 3 minutes or until lightly browned. Stir in raisins, juice, and vinegar; cook 30 seconds, stirring constantly with a whisk. Pour butter mixture over kale. Sprinkle with salt and pepper; toss well to coat.