For the salmon on celery sauce with spinach mashed potatoes, wash the fish and remove any remaining bones. Mix sea salt with water and place in a container so that the fish is covered with water.
Close the container and let it rest in the refrigerator. Wash the potatoes, boil them in their skins, peel them while still hot and put them through a press.
While the potatoes are cooking, heat the milk, butter and soup powder in a saucepan. Fold into the mashed potatoes, season with salt and pepper and nutmeg.
Place in a preheated stainless steel bowl and keep warm in the oven. Peel the garlic and crush finely with the back of a knife. Wash the spinach, dry it well and sort it if necessary.
In a non-stick skillet, render butter and sauté garlic, add spinach and allow to break down. Season with salt, pepper nutmeg and parmesan.
Add the spinach leaves to the mashed potatoes, if it is not creamy enough add some more butter or warm milk. For the sauce, wash the celery, clean it and cut it into pieces, peel the parsley root and cut it into pieces as well.
Melt the butter in a saucepan, sauté the vegetables in it, add vegetable soup and reduce to about half the amount.
Puree everything in a tall container with a hand blender and press through a sieve. Return the mixture to the saucepan, mix the white wine with the potato starch and add to the mixture. If necessary n