Preheat oven to 350 degrees. Using 2 tablespoons oil, brush insides of pita rounds. Cut each round into 6 wedges. Arrange wedges in a single layer on a baking sheet, oiled sides up; toast until golden brown and crisp, 7 to 10 minutes.
Meanwhile, pulse feta, yogurt, lemon juice, and remaining 3 tablespoons oil in a food processor just until mixture is thick and spreadable, about 10 pulses. Transfer to a medium bowl, and stir in parsley and radishes. Serve with pita crisps.
This is a great recipe. A twist on it is to just use yogurt, grated radishes, finely chopped green onion and salt. It gives it a slightly different taste than with the lemon and feta cheese.