Preheat oven to 450 degrees. Line a rimmed baking sheet with parchment paper and set aside.
In a large bowl, toss the potato wedges, 1/4 C olive oil, salt and pepper. Transfer to the baking sheet and spread into a single layer.
Roast for 40 -45 minutes or until the potato wedges are brown and crisp.
Add the remaining olive oil, garlic and parsley to a small food processor. Pulse several times.
Transfer to the large bowl used for the potato wedges and stir in the scallions. Set aside.
In a small bowl, whisk together the yogurt, dill, lemon juice and garlic. Season to taste with salt and pepper.
When the potatoes are done, add them to the large bowl and toss to coat.
Transfer to a platter and sprinkle with crumbled feta. Serve with homemade tzatziki.