Cook 8 oz pasta in salted water to al dente according to the package directions. Drain and rinse with cold water.
Chop 3 celery stalks and 4 hard boiled eggs into small pieces.
In a large bowl, stir together ¾ cup mayonnaise, 1 Tablespoon Dijon mustard, 2 Tablespoons lemon juice, ½ teaspoon garlic powder, 1 teaspoon dried dill, and ¼ teaspoon black pepper.
Mix in the 10 oz tuna, 1 cup frozen peas, celery, and eggs.
Add the pasta and stir until well coated. Taste and adjust the salt and pepper as needed.
Cover and chill at least 1 hour before serving.
Store leftover in the refrigerator for up to 5 days.