For the homemade soup powder, preheat the oven to 75° C convection, or 85° C for top and bottom heat.
Then finely chop the onions with the sea salt in a blitz chopper. Peel the carrots and celery, wash the leek and cut everything into small pieces and puree them together with the onion-salt mixture.
Wash the parsley, shake dry and chop coarsely. Rinse the tomatoes, cut them in half and remove the stem. Also mash the tomato-parsley mixture with the rest and, if necessary, pass everything together through a fine sieve.
Spread the mixture in a roasting pan lined with wrapping paper and leave to dry in a heated oven for one night, about 8 hours, leaving the oven door ajar.
In a screw jar you can store the now dried homemade soup powder for at least ten weeks.
Preparation Tip:
The homemade soup powder is ideal for seasoning, but as a base for a clear soup it is not flavorful enough.