Finely chop the mushrooms then mix with the salt and hang in a muslin cloth over a bowl overnight to drain. Reserve the liquid but discard the mushroom pulp.
Bring the soy, sugar and sherry vinegar to the boil and then use the mixture to season the mushroom juice to your own taste
Add the agar agar to the liquid, bring to the boil and whisk constantly for about 10 seconds until fully dissolved, pour into a tray and place in the fridge to set.
Once set, place in the blender and blend to a thick purée consistency, retain at room temperature.
To make the wild garlic purée
Melt the butter in a large pan and add the spinach and the garlic leaves. Sweat until fully cooked. You can check this by rubbing the leaves between your fingers – if it totally disintegrates it's cooked.
Place the sweated leaves into a blender with the double cream and blend on full power for around two to three minutes until totally smooth. Season.
Push the purée through a fine sieve and then cool down as quickly as possible.
Just before you are ready to cook the beef, warm the purée in a pan, check the seasoning, put it into a squeezy bottle and keep warm.
To make the beef and asparagus
Remove the beef from the fridge and allow to rest, uncovered, for at least two hours before cooking.
Peel the asparagus and trim off the woody ends.
Preheat a medium-sized frying pan to a medium heat then add in the beef dripping.
Heavily season the beef with salt and pepper then put it into the pan, fat side down. Allow the fat to render out for around three to four minutes, then add 100g butter to the pan with the thyme and garlic. Colour the beef on all sides, turning every minute to ensure even cooking. Once coloured, turn the heat down to low and continue to cook as desired (for medium rare, as per the picture, the core temperature will be 45°C). Rest the meat in a warm place for as long as you cooked it, brushing with its butter every five minutes.
Bring 300g butter, 300ml water and 9g salt to the boil to make an emulsion. Add the asparagus then turn down to a low heat. Cook for five to eight minutes, then remove from the emulsion, place on a warm tray and coat in the hazelnuts. Keep the emulsion.
Trim both ends of the beef then cut into four evenly sized slices. Very lightly season the exposed pink meat with salt and place on warmed plates
Place two spears of asparagus next to the beef then put a large dot of wild garlic purée just above it.
Cook the girolles, kohlrabi and turnip leaves in the emulsion for 30 seconds, then drain and scatter over the beef and asparagus.
Place a teaspoon of the mushroom ketchup on the plate and garnish with the garlic flowers and nasturtium leaves.