Begin by bringing a large pot of salted water to a rolling boil. Add the whole wheat rotini pasta and cook according to package instructions, usually about 8-10 minutes, until al dente. Once done, drain the pasta in a colander and rinse it under cold water.

In a large mixing bowl, combine your cooled rotini pasta with chopped cucumber, celery, red bell pepper, cooked frozen peas, and canned flaked tuna. Use a spatula to gently fold the ingredients together.

In a separate small bowl, whisk together the plain Greek yogurt, light mayonnaise, fresh lemon juice, and Dijon mustard until smooth and creamy.

Stir in chopped fresh dill, garlic powder, salt, and pepper to taste into the dressing until all spices are well incorporated.

Pour the dressing over the pasta and vegetable mixture. Gently toss everything together until each piece is well-coated with the creamy dressing.

Cover the bowl with plastic wrap or a lid and refrigerate the salad for 20-30 minutes.

Once chilled, give the salad a gentle toss before serving and garnish with extra fresh dill or a squeeze of lemon juice if desired.