Bring a large pot of salted water to a boil. Add the rotini pasta and cook according to package instructions, about 8-10 minutes until al dente. Drain and rinse under cold water, set aside.

While the pasta cooks, wash and chop the cherry tomatoes, cucumber, bell pepper, and red onion into bite-sized pieces. Place in a large mixing bowl.

In a small bowl, combine olive oil, red wine vinegar, minced garlic, and Dijon mustard. Whisk until emulsified and season with salt and pepper to taste.

Add the cooled pasta to the bowl with vegetables. Pour the dressing over and toss gently to combine.

Cover and chill in the refrigerator for at least 30 minutes before serving.