Heat the butter in a pressure cooker.
Cut the celeriac into chunks and turn on.
Add the salt and baking soda and stir well until they have dissolved.
Place the lid on the pressure cooker and cook for 20 minutes on low heat.
The pressure cooker should continue to steam a little.
Place the pan under cold running water.
As soon as there is no pressure left on the pan, you can remove the lid.
You can check this by first opening the valve and making sure that no steam comes out, after remove the lid.
Blend the celeriac smoothly in the blender and add the vegetarian dashi and the cooking cream to the desired thickness.
Cool down and store in the refrigerator.