Place the halved baby potatoes in a medium pot and cover with cold water by about 1 inch. Add 1/2 teaspoon kosher salt. Bring to a simmer over medium-high heat and cook until potatoes are just tender when pierced with a fork, about 12–15 minutes depending on size. Drain and immediately plunge into a bowl of ice water to stop cooking. Once cool, drain and set aside to steam-dry for a few minutes, then keep warm.

Cook pasta

While potatoes cook, bring a large pot with 8 cups water and 1/2 tablespoon kosher salt to a rolling boil. Add the dried pasta and cook until al dente (1–2 minutes less than package directions), about 8–10 minutes depending on shape. Reserve 1/4 cup of the pasta cooking water, then drain the pasta in a colander and rinse briefly under cool water to stop cooking and remove excess starch. Transfer to a large mixing bowl.

Prepare Vegetables & Add-ins

While pasta and potatoes are cooking, chop the celery, red bell pepper, red onion, dill pickles, and parsley. Thaw the peas if frozen and chop the hard-boiled eggs if using. Add all these prepared vegetables and eggs to the bowl with the drained pasta. Add the cooled, halved potatoes and gently fold so shapes remain intact — avoid overmixing to prevent potatoes from breaking up.

Make Dressing

In a medium bowl, whisk together the mayonnaise, Greek yogurt, Dijon mustard, apple cider vinegar, lemon juice, granulated sugar, smoked paprika, celery seed (if using), and 1/2 teaspoon black pepper until smooth. Taste and adjust acidity or sweetness as needed — add a pinch more sugar if too tangy, or a splash more vinegar or lemon if too rich. If the dressing seems very thick, whisk in up to 1–2 tablespoons of the reserved pasta water to loosen slightly so it coats ingredients easily.

Combine & Chill

Pour the dressing over the pasta, potatoes, and vegetables. Gently fold until everything is evenly coated. Taste and season with the 1/2 teaspoon salt and additional 1/4 teaspoon black pepper (or to taste). Cover the bowl and refrigerate for at least 1 hour (preferably 2–4 hours) to allow flavors to meld. Stir once before serving and adjust seasoning if needed, adding a splash more vinegar or salt.

Finish & Serve

Before serving, sprinkle chopped chives or green onions and a light dusting of paprika over the salad. Serve chilled or at cool room temperature. Keeps well covered in the refrigerator for 3–4 days; the potatoes will soften over time.