In a large mixing bowl, combine 2 cups of thawed frozen peas, 1 cup of diced cheddar cheese, 1 cup of chopped celery, 1 cup of chopped red bell pepper, and ½ cup of finely chopped red onion. Stir until evenly mixed.

In a separate small bowl, whisk together ½ cup of mayonnaise, ½ cup of sour cream, 2 tablespoons of apple cider vinegar, 1 tablespoon of sugar, and a pinch of salt and black pepper until smooth.

Pour the dressing over the vegetable mixture in the large bowl. Gently toss using a spatula until everything is well-coated.

Cover the bowl with plastic wrap or transfer to an airtight container. Refrigerate for at least 1 hour to allow flavors to meld.

Before serving, stir gently and spoon the vibrant Irish Pea Salad into a serving dish.