Thaw the frozen peas under cool running water for 3-5 minutes, then drain well.

In a large mixing bowl, combine the thawed peas, diced cheddar cheese, chopped celery, chopped red bell pepper, and finely chopped red onion.

In a medium bowl, whisk together the mayonnaise, sour cream, apple cider vinegar, sugar, and a pinch of salt and black pepper until smooth.

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

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

Before serving, stir gently to redistribute the dressing and transfer to a serving dish.