What are the cooking instructions for the Whole Cooked Beef Wellington (2003100)? 09 December 2019 15:47 Updated Cook at 185 degrees (fan assisted oven) for 50 minutes. Please note that the cooked beef wellington will not come out pink. Related articles What are the cooking instructions of the Whole Beef Wellington, Oven Ready (2141614)? When will the Fortnum's Beauty Advent Calendar 2023 go on sale?