In a large mixing bowl, combine the green and red cabbage, carrots and green onions.
In a small bowl, toss the diced apple with the lemon juice and add to the cabbage mixture.
In a small bowl, combine the sugar, vinegar, salt and pepper and whisk til sugar is dissolved.
Pour that mixture over cabbage mixture and toss to thoroughly combine. Cover and refrigerate for 20-30 minutes.
In a small bowl, combine the mayonnaise, sour cream, horseradish and mustard. Add to the slaw mixture and mix to thoroughly combine.
Cover and refrigerate for at least 1 hour or overnight before serving.