Roast the potatoes: Preheat your oven to 425°F (220°C). In a large bowl, toss the halved or quartered potatoes with olive oil, salt, pepper, smoked paprika, and garlic powder until every piece is evenly coated. Spread the potatoes in a single layer on a baking sheet lined with parchment or foil. Roast for 25–30 minutes, flipping halfway through, until golden, slightly crispy on the edges, and tender inside. Remove from the oven and let cool slightly so they don’t wilt the salad dressing.

Prepare the dressing: In a small bowl, whisk together mayonnaise, Dijon mustard, and apple cider vinegar (or lemon juice) until smooth. Taste and adjust seasoning with a little salt or pepper as needed. If you like a tangier flavor, add a touch more vinegar. For a lighter dressing, you can substitute half the mayonnaise with Greek yogurt.

Combine the salad ingredients: In a large mixing bowl, combine the roasted potatoes with red onion, celery, parsley, and optional ingredients like capers or chopped dill pickles. Pour the dressing over the warm potatoes and gently toss until everything is evenly coated. The warmth of the potatoes helps them absorb the flavors beautifully without becoming mushy.

Chill or serve immediately: You can serve this roasted potato salad warm, at room temperature, or chilled. For best flavor, cover and refrigerate for at least 30 minutes before serving. Garnish with extra parsley or a sprinkle of smoked paprika for a colorful, appetizing look.