Preheat the oven to 200C/180C Fan/Gas 6.
Heat the oil in a medium frying pan. Once hot add the beef and cook on each side for 2-3 minutes.
Add 75g/2¾oz butter to the pan and place in the oven for 4-5 minutes depending on the weight of your fillet steak. Leave to rest.
Add 75g/2¾oz butter to a hot pan. Add the salsify and and stir-fry for 3-4 minutes, or until tender and golden-brown.
In a clean pan, heat the remaining butter until foaming then add the shallot. Fry for 3-4 minutes, or until golden-brown.
Add the Madeira and carefully tip the pan towards the flame of the hob, so that the alcohol catches alight. Cook until the liquid has reduced in volume by three-quarters. Add the veal stock, stirring well, and cook for 3-4 minutes, or until reduced in volume by half. Season, to taste, with salt and black pepper. Stir in the chervil.
For the rosti, put the potatoes in a clean tea towel inside a bowl and squeeze out any excess water. Transfer the potato and beetroot into a clean bowl along with the crème fraîche, egg, parsley, salt and pepper. Stir until well combined.
Heat 35g/1¼oz butter in an ovenproof frying pan over a medium heat and place 2 x 7.5cm/3in chefs' rings in the pan. Spoon the potato mixture into the rings, press down well using a spoon, and cook for 3-4 minutes, or until golden-brown. Remove the rings, turn the rosti, press the mixture down and cook for a further 3-4 minutes. Transfer the pan to the oven for 5-10 minutes, or until tender and cooked through.
Meanwhile, boil the baby beetroots in their skins for 10-15 minutes. Run under cold water and rub off the skins. Heat a medium frying pan and add the remaining butter, add the baby beetroots and cook for 1-2 minutes. Peel the heritage beetroots and cut using a mandolin.
To serve, place the rosti in the centre of the plate and place the beef on top. Put the salsify and beetroot around the rosti and pour over the sauce.