Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente. Drain and rinse under cold water to cool.

While the pasta is cooking, dice the celery, red bell pepper, and slice the green onions.

In a mixing bowl, combine the mayonnaise, apple cider vinegar, mustard, salt, and black pepper. Mix well until smooth.

In a large mixing bowl, combine the cooled macaroni, diced vegetables, and dressing. Stir until everything is well coated. If using, add peas and cheddar cheese.

Cover the salad and refrigerate for at least 1 hour before serving to allow the flavors to meld.