In a large pot, cook the pasta in salted boiling water until al dente. Pasta cooking time varies, so follow the directions on the box to get the time right.
Drain the pasta and rinse with cold water. Pour into a large bowl.
While the pasta is cooking, wash the celery and green onions. Dice the celery and pickle; slice the green onions.
In a small bowl, whisk together the mayonnaise, milk, sour cream, dry ranch dressing mix, and dry dill.
Add the celery, onions, pickles, peas, and tuna to the pasta. Pour the dressing over the top, then stir until everything is well coated.
Cover and chill for 30 minutes to blend flavors. (Or serve immediately.)
Notes
You don't need to thaw the peas, they will thaw quickly once added to the pasta.
Feel free to use Miracle Whip instead of mayo. You can also use sweet pickles or relish in place of dill. Make the salad your own and add any ingredients you like!