Preheat oven to 375ºF. Place the pie crust into a 9" deep dish pie pan or tart pan. Press down and crimp edges. In a medium bowl, beat the eggs with the milk until runny. Season with salt, pepper and oregano. Into the eggs, mix the tomatoes, olives and chopped green onions. Pour the egg mixture into the pie crust, and sprinkle the feta over top. Bake at 375ºF until set in the middle, about 40-45 minutes. Allow quiche to cool slightly before slicing and serving (7 minutes).
Place the quiche on a cookie sheet before putting in the oven, it makes it easier to get out and helps keep your oven clean!