Boil a large pot of salted water, add elbow pasta, and cook until al dente, about 7-9 minutes. Drain and rinse under cold water.

Return pasta to pot, stir in half of the dill pickle juice, and let sit for 5 minutes. Drain excess juice.

In a large mixing bowl, combine mayonnaise, sour cream, remaining dill pickle juice, Sriracha, salt, black pepper, and fresh dill. Mix until smooth.

In a large serving bowl, mix cooled pasta with cheddar cheese, sliced dill pickles, fresh dill, and onion. Fold together gently.

Pour dressing over the pasta mixture and mix thoroughly. Taste and adjust seasoning if needed.

Cover with plastic wrap or a lid and refrigerate for at least 4-6 hours, preferably overnight.