Combine cabbage, fennel, onion, and carrot in large bowl. Whisk mayonnaise, sour cream, lemon juice, sugar, and hot sauce in medium bowl to blend. Season dressing to taste with salt and pepper. Add dressing to cabbage mixture; toss to coat. Season slaw to taste with salt and pepper. Refrigerate at least 1 hour and up to 2 hours, tossing occasionally. Transfer to serving bowl.