Start by bringing a large pot of salted water to a rolling boil over high heat. Once boiling, add the whole wheat rotini pasta and cook according to the package instructions until al dente, about 8-10 minutes. Once cooked, drain the pasta in a colander and rinse it under cool water to stop the cooking process and prevent clumping.

In a large mixing bowl, combine the cooled rotini pasta with chopped cucumber, celery, red bell pepper, and cooked frozen peas. Use a spatula to gently mix together until blended, ensuring that the vegetables are evenly distributed throughout the pasta.

In a separate bowl, whisk together the plain Greek yogurt, light mayonnaise, fresh lemon juice, Dijon mustard, and chopped dill until the mixture is smooth and creamy. Add garlic powder, salt, and pepper according to your taste preference.

Pour the freshly made dressing over the pasta and vegetable mixture. Gently fold the dressing into the Tuna Pasta Salad with Peas using a spatula, making sure that every ingredient is well coated.

Cover the bowl with plastic wrap or transfer the Tuna Pasta Salad with Peas to an airtight container. Refrigerate for at least 20-30 minutes before serving to let the flavors meld together.

After chilling, take the salad out of the refrigerator and give it a gentle stir. Serve your delicious Tuna Pasta Salad with Peas in bowls or on platters for a colorful presentation.