Orange Buttermilk Pie

I created this pie in the middle of the winter, when clementines and satsuma oranges are in season. The flavor is simple and pure, and you can use any oranges that you like. Buttermilk is the key ingredient, so use the good stuff you can sometimes find in farmers’ markets if possible. I count on the old-fashioned buttermilk that we get from our friends at Southern Swiss Dairy to give this pie the old-timey flavor I recall from childhood.