Pre-heat oven to 350°F. Prepare the batter: Combine potatoes and onion; mix together well. Add beaten eggs and milk, salt and pepper to taste. Add flour and mix thoroughly. Pour the mixture into a deep dish and bake it in centre shelf of oven for 45 min., or until edges are golden brown. Serve with fresh parsley and sour cream. Optionally you can add meat or mushrooms, or both. Brown them first on high heat together with spices (black pepper, paprika, herbs to taste) and a bit of salt. Use olive oil for frying. Add it to the batter, pour the mixture into a deep dish and stir well. Bake in centre shelf of oven for 1 hour. Serve with fresh parsley and sour cream.