In a large pot of lightly salted boiling water, cook the pasta as the package directs. Drain and rinse the pasta well under cold running water. Drain well so your salad doesn't end up soggy.
While the pasta is cooking, in a medium bowl, stir together the mayonnaise, vinegar, salt and pepper. Add pasta, tomatoes, carrot, basil and onion. Toss to combine and coat with dressing.
Recipe Notes
Nutritional Estimates Per Serving (¾ cup): 5 SmartPointsThis recipe is best freshly made. To make it ahead, keep the dressing separate and toss shortly before serving. For best flavor be sure to use nice ripe tomatoes. Diced beefsteak or halved grape tomatoes can be substituted for plum tomatoes.