If Frozen…defrost turkey crown.
Preheat oven at 200 degrees
Put turkey in large, deep pan, add water and surround with large slices of onion and carrot.
Cover the pan with sheet of baking parchment and silver foil, making sure the turkey and the contents of the pan is well sealed. This is important.
Then, place the pan on the stove, bring to the boil and allow to boil for 5 minutes.
This is very important, because it creates the steam.
Then place the turkey in the oven and cook at 200 degrees for 2 hours.
Remove the turkey from the oven and discard the foil and parchment.
Turn the oven up to 220 Degrees.
Brush the turkey with oil and replace in the oven.
Cook for a further 20 minutes.
Your turkey ought to be perfectly cooked and a golden brown.
Leave to rest.
It would appear that the timings are exact for a very good reason.
Voila!