Blanch the broccoli and cauliflower florets by immersing them in boiling water for 2 minutes, then transferring them to an ice bath to cool. Drain well and pat dry.

In a large mixing bowl, combine the blanched broccoli and cauliflower with shredded cheddar cheese, chopped red onion, and crumbled bacon.

In a separate bowl, whisk together mayonnaise, sour cream, apple cider vinegar, sugar, salt, and pepper until well combined.

Pour the dressing over the vegetable mixture and gently toss until all ingredients are evenly coated. Refrigerate the salad for at least 1 hour to allow the flavors to meld.

Before serving, give the salad a final gentle toss. Garnish with additional bacon and cheese if desired.