Halve the onions, roast the cut surfaces dark in a large saucepan without fat. Clean and roughly chop the parsley roots, celeriac, leek and carrots. Peel the garlic cloves and ginger, cut into slices.
Put everything with the juniper berries, bay leaves, peppercorns, parsley and lovage in the pot and fill up with water. Simmer for 2 - 3 hours, skim off the foam.
Finally, pour through a sieve. Fill into clean glasses. I freeze the jars and use the broth when needed.