1. Cook the pasta: Bring a large pot of salted water to a rolling boil. Add the pasta and cook according to package directions until al dente (about 10-12 minutes).

2. Drain and cool the pasta: Once cooked, drain the pasta thoroughly in a colander. Rinse it under cold water to stop the cooking process and cool it down quickly. Let it drain well.

3. Prepare the vegetables: While the pasta cooks, prepare your fresh ingredients. Halve the cherry tomatoes, dice the English cucumber, thinly slice the red onion, pit and halve the Kalamata olives, and chop the fresh parsley.

4. Make the dressing: In a small bowl, whisk together the olive oil, red wine vinegar, Dijon mustard, dried oregano, and garlic powder. Season with salt and black pepper to taste. Whisk until the dressing is well combined and slightly emulsified.

5. Combine ingredients: In a large mixing bowl, add the cooled pasta, drained tuna, halved cherry tomatoes, diced cucumber, sliced red onion, halved Kalamata olives, and chopped fresh parsley.

6. Dress the salad: Pour the prepared dressing over the pasta and vegetable mixture.

7. Toss everything together: Gently toss all the ingredients until everything is evenly coated with the dressing. Ensure the tuna breaks up slightly and distributes throughout the salad.

8. Chill before serving: For the best flavor, cover the bowl and refrigerate the pasta salad for at least 30 minutes to allow the flavors to meld. A longer chill time (1-2 hours) is even better!