Mix together all the ingredients in the dough mixer and mix to a smooth dough. Put the dough in a vacuum bag and seal. Leave to rest in the fridge for at least 30 minutes.
Cut the mushrooms and onions into rough chunks, sweat them on low heat in the pressure cooker. Add a few pinches of salt along with the water. Put the lid on the pressure cooker and cook for about 45 mins. Strain the broth and season with fermented Porcini and salt. Reduce if necessary. Dry any mushrooms left over from the cooking process.
Peel the celeriac and shave on the mandolin as instructed. Save all the leftovers from the celeriac until later. Place the celeriac slices on a cloth in portions, season with salt. Steam in the oven for about 7 minutes at 100°C steam.
Put all the celeriac bits in a saucepan together with the oil. Cook the celeriac in the oil until soft, strain. Blitz the celeriac with a little of the oil and cold water into a smooth cream in a blender. Chop the nuts and grate the cheese into the celeriac cream. Season with mushroom powder, salt and pepper.
Baked, pickled onions
Peel the onions and divide them in half. Melt butter together with sugar, vinegar, thyme and salt. Place the onions together with the melted butter in a vacuum bag and seal. Bake the onions in the oven at 100°C steam for about 7 minutes. Remove the onions from the bag and char them with a gas burner.
Put the thyme, rosemary and oil in a blender jug and mix all the ingredients for about 5 minutes. Strain.
Roll out the pasta dough on the pasta machine to the desired thickness. Punch out the dough and pipe the filling onto the pasta shapes. Fold the pasta as instructed. Place the ravioli on a baking sheet dusted with flour and leave to dry for about 40 minutes.