Cook the Pasta : Cook the pasta according to the instructions on the package. Once cooked, drain and set it aside. Reserve about 1/4 cup of pasta water for later use.

Prepare the Ingredients : While the pasta cooks, chop the pickles, red onion, and dill. Drain the tuna and set it aside.

Make the Sauce : In a large bowl, whisk together olive oil, mayonnaise (if using), and mustard (if using). Add salt, black pepper, and dill, mixing until combined.

Combine Everything : Add the cooked pasta to the sauce, tossing to coat. Gently fold in the tuna, pickles, red onion, and Parmesan cheese. If the mixture seems dry, add a splash of the reserved pasta water to loosen it up.

Serve : Taste and adjust seasoning if needed. Serve warm or cold as a main dish or side. Garnish with extra dill and Parmesan for a finishing touch.