Preheat oven to 375°. In a skillet, heat oil over medium heat. Saute onion until tender, 1-2 minutes. Remove and set aside. In the same skillet, brown beef and pork together until no longer pink, breaking meat into crumbles; drain. Combine onion, meat, potatoes, vegetables and seasonings. , On a lightly floured surface, roll half the dough to a 1/8-in.-thick circle; transfer to a 9-in. pie plate. Trim even with rim. Roll remaining dough to a 1/8-in.-thick circle. Fill bottom crust with meat mixture. Place crust over filling; trim, seal and flute edge. Cut slits in top. If desired, brush with egg. , Bake until golden brown, 30-35 minutes.