Cook the Pasta: Bring a large pot of salted water to a vigorous boil. Add whole wheat pasta and cook according to package instructions until al dente, approximately 8–10 minutes. Drain in a colander and rinse with cold water to stop cooking. Set aside to cool completely.

Prepare the Red Onion: Soak red onion in a bowl of cold water for at least 5 minutes. Drain and pat dry.

Whisk the Dressing: In a mixing bowl, whisk together Greek yogurt, lemon zest, lemon juice, honey, Dijon mustard, kosher salt, oregano, and black pepper until smooth.

Combine the Vegetables: In a mixing bowl, combine cherry tomatoes, sun-dried tomatoes, red bell pepper, red onion, capers, and fresh parsley. Toss gently.

Mix in the Pasta: Add the cooled pasta to the vegetable mixture and pour in the dressing. Gently fold to combine.

Flake the Tuna: Drain canned tuna and flake into large chunks. Fold gently into the salad.

Chill and Serve: Cover Salad and refrigerate for at least 1 hour before serving.