Cook the Pasta:

Bring a large pot of salted water to a boil. Add the tricolor rotini pasta and cook according to package directions until al dente. Drain the pasta in a colander and immediately rinse under cold running water for several minutes to cool it completely. Set aside.

Prepare the Vegetables:

While the pasta is cooking, peel and seed the cucumber, then chop it into small pieces. Slice the cherry or grape tomatoes in half. Finely dice the red onion and drain the black olives.

Combine the Ingredients:

In a large mixing bowl, add the cooled pasta, chopped cucumber, halved tomatoes, crumbled feta cheese, sliced olives, and diced red onion.

Add Dressing and Mix:

Start by pouring 1/2 cup of Italian dressing over the salad. Gently toss all ingredients together until well combined. Taste and add more dressing if desired, up to 1 cup total.

Chill or Serve:

You can serve the pasta salad immediately or cover and refrigerate for 2–4 hours to chill. If chilled, stir before serving and add an extra tablespoon or two of dressing to freshen it up.