Cook the pasta according to package directions. Make sure to salt your water generously – this is your only chance to season the pasta itself. Drain and rinse under cold water to stop the cooking process and cool it down quickly.
Prepare your vegetables while the pasta cooks. Dice the cucumber into bite-sized pieces, halve the cherry tomatoes, slice the red onion thinly, and halve the Kalamata olives. This is a great time-saver!
Make the dressing in a small bowl or jar. Whisk together the olive oil, red wine vinegar, lemon juice, minced garlic, oregano, and Dijon mustard. Season with salt and pepper to taste.
Combine everything in a large bowl. Add the cooled pasta, all the prepared vegetables, and crumbled feta cheese. Pour the dressing over everything.
Toss gently but thoroughly. Make sure every piece of pasta and vegetable gets coated with that delicious dressing. Use a large spoon or your hands to mix everything together.
Let it chill for at least 30 minutes before serving. This resting time allows the flavors to meld together beautifully. If you're in a rush, you can eat it right away, but trust me – it's worth the wait!