Preheat the oven to 220'C.
Finely dice the garlic and chop the flat parsley. Use a sharp knife to make incisions in the beef . Insert the sage into the incisions and then season the meat with salt.
Heat a frying pan and add a little olive oil. Colour both sides of the fillets and then remove from the pan. Allow to rest for at least 5 minutes before placing in the oven and cook for 5 to 8 minutes depending on the thickness of the steak.
Wash all of the mushrooms and trim if necessary. Heat a pan, add olive oil and cook the mushrooms in batches making sure not to overcrowd the pan. Make sure they are a nice golden brown colour. Season with salt and pepper each time you add a batch. Finish with the garlic, chopped parsley and a little truffle oil if necessary.
For the sauteed potatoes: place the potatoes in a pan of cold, salted water. Bring to the boil and cook until the potatoes are tender. Heat a frying pan and add a little olive oil. Add the potatoes to the pan and then add a little butter. Season with salt and pepper and cook until golden brown.
In small saucepan, bring water to boil. Add parmesan; stir to combine. Remove from heat; let it sit for 15 minutes. Pass through sieve into bowl; discard the solids. Add the lecithin powder, stir until its dissolved. Using a blender, blend until foam forms. There will be some liquid underneath, blend again if necessary once top layer of foam has been removed.
Boil together the wine and veal jus till reduced by half the volume, set aside half of the mix to use a a traditional sauce, add the agar to the remaining half and bring back to the boil, reduce to a simmer for 5 minutes to set the agar reaction off, pour into jelly moulds and chill till needed.
Top and tail the beans, blanch in boiling salted water till tender, around 3 minutes, drain and toss with the butter.
Place the steak on the side of the plate, use a stainless steel ring next to the steak and add the saute potatoes to it, place the green beans in the middle, top them with the parmesan air, put the jelly on top of the fillet steak and spoon over the truffled mushrooms, finish with the remaining sauce.
«If your jelly doesn't set, reboil it and add a little more agar agar.»