Cook the elbow macaroni according to package instructions. Drain and rinse under cold water to cool.
In a large mixing bowl, combine the drained tuna, thawed peas, mayonnaise, sour cream, Dijon mustard, lemon juice, garlic powder, onion powder, salt, and pepper. Mix well until all ingredients are combined.
Add the cooled macaroni to the tuna mixture and stir until the pasta is evenly coated.
If using, fold in the chopped parsley for added flavor and color.
Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld.
Serve chilled or at room temperature.