First thing in the morning remove the beef from the fridge to allow to come to room temperature. Rub it all over with the oil and the salt and pepper
Make the crust (can be done the day before) in a pan fry the onions in the butter. Add to the breadcrumbs and mix 200mls of water with the mustard.
Break the eggs into the bread crumb mix and season well add the mustard and stir to make a paste.
Spread the crust evenly over the beef, leaving the ends uncovered, cover the crust with well-greased foil. Place the carrots in the tray and sit the beef on it. Place in the oven for 2 and half hours
Remove the foil and cook for one final hour; take the beef from the oven and leave to rest for 20 minutes while you make the gravy.
Yorkshire Pudding
Pre heat the oven to 220ºc
Beat the eggs with the milk and the salt, sieve the flour twice to aerate and remove impurities. Beat the flour into the milk to make a batter. Sieve if necessary.
Place the Yorkshire tray in the oven until hot and add a good amount of fat into each dip.
Return to the oven and heat until the fat smoking.
This is where you must be careful, as the fat is very hot.
Ladle some mix into each mould so that they are nearly full, return to the oven and reduce the heat to 200ºC cook for 15 minutes.