Combine the filling ingredients and white sauce. Spread out on plate and chill thoroughly.
Beat the egg and water together, place in shallow bowl.
To make the croquettes, spoon up a generous portion (2-3 T depending on desired size) of the filling mix. Form into round or torpedo-shaped patties, roll in flour, then egg, then bread crumbs. Place on baking sheet and chill for a half-hour.
Heat 2 inches of oil (I use High Temp oils like avocado and/or grape seed) in a large frying pan (I use a wok) and fry croquettes for 5 minutes, turning occasionally, until golden and crispy.
Keep warm in 150º F oven until serving time.
The Croquettes are delicious by themselves. They thrive on being accompanied by cranberry sauce. You could also use leftover gravy or a creamy mushroom sauce but not necessary.