Preheat oven to 450°F. In a bowl, toss the potato wedges with olive oil, juice from 1/2 of the lemon, garlic, salt, pepper, and oregano. Bake for about 30 minutes, flipping halfway through. When the potatoes are tender but not totally crisp, remove them from the oven and top with the bell pepper, red onion, olives, and feta cheese. Bake for another 5-7 minutes. Squeeze the remaining lemon juice over the top and add more salt before serving.
