Step 1

Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until tender (about 1 minute past al dente). Drain and let cool to room temperature.

Step 2

Meanwhile, in a large bowl, whisk together the mayonnaise, sour cream, sugar, mustard, vinegar, water, salt, pepper, and onion powder.

Step 3

Add the cooked pasta, carrots, celery, bell pepper, scallions, and basil to the bowl and stir until evenly combined. Taste and adjust seasoning if necessary. Serve the salad immediately or let it sit for up to an hour at room temperature before serving. (Keep in mind that the dressing will thicken and get absorbed by the noodles as the salad sits.)

Step 4

Make-Ahead Instructions: The dressing can be made up to 3 days ahead and refrigerated; the pasta, vegetables, and basil can be prepared up to 1 day ahead and refrigerated. Before serving, bring all of the components to room temperature. Add the dressing to a large bowl and whisk to loosen, then stir in the pasta, vegetables and herbs. Taste and adjust seasoning, if necessary, and serve.

Step 5

Update Note: In response to feedback from readers, this recipe was retested and updated on &frac73;/22 to include less sugar.