Thaw the frozen peas under cool running water for about 3 to 5 minutes. In a large bowl, combine the peas, cheddar cheese, celery, red bell pepper, and red onion. Stir gently to mix.

In a separate bowl, whisk together the mayonnaise, sour cream, apple cider vinegar, and sugar. Add salt and black pepper to taste. Whisk until the dressing is smooth.

Pour the dressing over the salad ingredients and gently toss until everything is evenly coated.

Cover the bowl and refrigerate the salad for at least one hour to allow flavors to develop.

Before serving, give the salad a gentle stir and transfer to a serving dish.