Bring a large pot of salted water to a rolling boil. Add the whole wheat rotini and cook according to package directions until al dente, usually 10-12 minutes. The pasta should have a slight bite since it will continue absorbing flavors as it sits. Drain thoroughly and rinse with cold water to stop the cooking process and cool it quickly.

While the pasta cools, prep your vegetables. Cut cherry tomatoes in half to release their juices, dice the cucumber into bite-sized pieces, and chop the bell pepper uniformly. Slice the red onion as thinly as possible - this prevents it from overpowering the other flavors. The key is keeping all pieces roughly the same size for balanced bites.

In a small bowl, whisk together olive oil, fresh lemon juice, red wine vinegar, minced garlic, and dried oregano. Season generously with salt and pepper. The dressing should taste slightly more acidic than you'd prefer since the pasta and vegetables will mellow it out. Let it sit for a few minutes to allow the garlic to infuse.

In a large mixing bowl, combine the cooled pasta with all prepared vegetables, olives, and feta cheese. Pour the dressing over everything and toss gently but thoroughly. Add fresh basil last to prevent bruising. Taste and adjust seasoning - you'll likely need more salt and pepper than expected.