Boil a large pot of salted water. Add the medium shell pasta and cook until al dente, about 8–10 minutes. Drain and rinse under cold water.

In a mixing bowl, combine the mayonnaise, sour cream, apple cider vinegar, sugar, salt, and pepper. Whisk until smooth and creamy.

Add the cooled pasta to the dressing and gently mix until fully coated.

Add the frozen peas, shredded cheddar cheese, and minced red onion. Stir gently to distribute evenly.

Cover and chill for at least 1 hour to allow flavors to meld.

Adjust seasoning with salt and pepper before serving. Garnish if desired and serve cold.