Preheat the oven to 350 degrees F (175 degrees C).
In a medium bowl, mix together the ground beef, egg, milk, onion, bread crumbs, salt and pepper. Press into a 9 inch pie pan like a crust. Prick meat all over using a fork.
Bake for 25 to 30 minutes in the preheated oven. Remove from the oven, and pour off any excess fat. Arrange the sliced peaches over the beef. Mix together the vinegar, ketchup and brown sugar, and spoon over the top of the peaches.
Bake for an additional 20 minutes. Let stand for at least 10 minutes before serving.