American Macaroni Salad

2 cups dry elbow macaroni, cooked, rinsed, and drained

1/3 cup diced celery

1/4 cup minced red onion, soaked in cold water for 5 minutes, drained

1 tablespoon minced flat-leaf parsley
1/2 cup diced vine-ripened tomato (optional)
1/2 cup prepared mayonnaise
3/4 teaspoon dry mustard
1 1/2 teaspoons sugar
1/2 tablespoons cider vinegar
3 tablespoons sour cream
1/2 teaspoon kosher salt, plus more to taste
Freshly ground black pepper

In a large bowl combine the macaroni, celery, onion, parsley and tomato, if using. In a small bowl, whisk together the mayonnaise, mustard, sugar, vinegar, sour cream and salt. Pour the dressing over the salad and stir to combine. Season with salt and pepper to taste. Serve. Store covered in the refrigerator, for up to 3 days.

This tasted pretty good right after it was made, but don't make it ahead of time to serve later! It loses all it's flavor after it's refrigerated and becomes a bland, unappealing mess.  Blech!

From foodnetwork.com