Place potato cubes in a large pot and cover with cold water by about 1 inch. Add 1 teaspoon salt to the water.

Bring to a boil over high heat, then reduce to a simmer. Cook for 12-15 minutes until potatoes are just tender when pierced with a fork.

Drain potatoes thoroughly and spread them in a single layer on a baking sheet to cool for 10-15 minutes.

While potatoes cool, make the dressing: In a medium bowl, whisk together Greek yogurt, Dijon mustard, apple cider vinegar, olive oil, minced garlic, salt, pepper, and paprika if using.

Transfer cooled potatoes to a large mixing bowl. Add chopped red onion, celery, and fresh dill.

Pour dressing over potato mixture and gently fold everything together until evenly coated. Be careful not to mash the potatoes.

Taste and adjust seasoning if needed. Cover and refrigerate for at least 30 minutes before serving to allow flavors to meld.

Serve chilled or at room temperature, garnished with extra dill if desired.