kfc cole slaw recipe

8 cups finely chopped green cabbage - ¼ cup finely chopped carrot - 2 tablespoons finely minced onion - ½ cup mayonnaise - ¼ cup buttermilk - ¼ cup whole milk - ⅓ cup granulated sugar - 2½ tablespoons lemon juice - 1½ tablespoons white vinegar - ½ teaspoon salt - ⅛ teaspoon ground black pepper