In a large bowl, combine the broccoli florets, shredded cheddar cheese, dried cranberries, crumbled bacon, sunflower seeds, and chopped red onion.
In a separate small bowl, whisk together the mayonnaise, sour cream, white wine vinegar, sugar, salt, and pepper until smooth.
Pour the dressing over the broccoli mixture and toss well.
Serve immediately or refrigerate it for at least one hour before serving.