Cook the elbow macaroni according to package instructions. Drain and let cool.

In a large mixing bowl, combine the cooked macaroni, chopped eggs, celery, red bell pepper, and green onions.

In a separate bowl, whisk together the mayonnaise, mustard, vinegar, salt, and pepper until smooth.

Pour the dressing over the pasta mixture and stir until everything is well coated. Chill in the refrigerator for at least 30 minutes before serving.