Preheat oven to 425°F. Toss sweetpotato cubes with 1½ tbsp olive oil, smoked paprika, salt, and pepper on a baking sheet. Spread in a single layer and roast for 25 minutes, flipping once halfway, until caramelized and tender.

While potatoes roast, combine sliced red onion with apple cider vinegar and a pinch of salt. Let sit at least 10 minutes to quick-pickle.

Whisk together tahini, lemon juice and zest, garlic, honey, and warm water until smooth and pourable. Season with salt and pepper. Add more water a teaspoon at a time if needed.

Dress the salad:

Let roasted sweetpotatoes cool 5–10 minutes. Add celery, parsley, green onions, and drained pickled onion. Drizzle generously with dressing and toss gently.

Serve:

Transfer to a serving platter. Scatter toasted pepitas over the top with a few extra parsley leaves and a final drizzle of olive oil. Serve warm or at room temperature.