1. Sauté onions in oil until golden.
2. Preheat oven to 350 degrees Fahrenheit.
3. Add sautéed onions to mashed potatoes and let cool a little. Add rest of ingredients and mix well.
4. On a lined and greased cookie sheet, use an ice cream scoop (or your hands) to form balls. Place on cookie sheet and brush each scoop with beaten egg. Bake in preheated oven for 40 minutes or until golden brown. If making in advance, freeze once cooled.
5. When ready to serve, defrost and then reheat uncovered for about 15 minutes, until heated through.