Begin by bringing a large pot of salted water to a boil. Add the whole wheat pasta and cook for 8-10 minutes, or until al dente. Once cooked, drain and rinse under cold water to cool completely.

While the pasta cools, soak thin slices of red onion in a bowl of cold water for about 5 minutes to mellow their flavor.

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

In a large bowl, combine cherry tomatoes, sun-dried tomatoes, red bell pepper, drained red onion, and capers. Toss gently.

Fold the cooled pasta into the vegetable mixture, stirring carefully to combine.

Flake the canned tuna into the salad, then pour the dressing over and gently toss until everything is well coated.

Cover the bowl and refrigerate for at least 1 hour before serving.