Cook the pasta: Bring a large pot of salted water to a rolling boil.
Cook the pasta according to package directions until just al dente. Protein pastas can overcook quickly, so start checking early.
Rinse and cool: Drain the pasta and rinse under cold water until no longer warm. This stops the cooking and keeps the salad from turning gluey.
Make the dressing: In a large bowl, whisk together Greek yogurt, mayonnaise, Dijon, lemon juice, pickle brine, garlic powder, black pepper, and a pinch of salt.
The brine adds brightness and a little saltiness—taste before adding more salt.
Prep the mix-ins: Finely chop the dill pickles, celery, and red onion. Roughly flake the drained tuna with a fork. Chop fresh dill.
Combine: Add the cooled pasta to the bowl with dressing.
Toss gently to coat. Fold in tuna, pickles, celery, onion, and dill until evenly distributed.
Adjust: Taste and adjust seasoning. Add more lemon juice for brightness, more pepper for bite, or a little extra pickle brine if you want more tang.
Chill: Cover and refrigerate for at least 30 minutes.
This helps the flavors meld and slightly thickens the dressing.
Serve: Give it a stir before serving. If it seems tight after chilling, loosen with a splash of water, milk, or an extra spoon of yogurt. Garnish with more dill or cracked black pepper.