01 - Cook rotini according to the package until tender but firm. Drain, rinse briefly with cool water, and drain very thoroughly. Cool promptly before adding cheese and mayonnaise.
02 - Halve tomatoes and mozzarella balls; drain any packing liquid from the cheese. Chop basil shortly before mixing.
03 - Whisk mayonnaise with balsamic vinegar, olive oil and garlic powder. Taste and season with salt and pepper.
04 - Fold cooled pasta, tomatoes and mozzarella with the dressing until evenly coated. Fold in basil gently.
05 - Cover and chill for at least thirty minutes. Toss again before serving and keep the serving bowl chilled.