Boil salted water. Add noodles and cook for 5 minutes. Add the peas and cook 2 more minutes or until pasta is al dente. Drain and place in a bowl of ice water.
In a small bowl, mix mayonnaise, Greek yogurt, dill, and salt & pepper together.
Drain the pasta and peas and then place back in the bowl. Add the tuna, red onion, and the dressing. Toss and add more salt & pepper to taste. Serve or chill until ready to serve.