Broth makes almost any soup better, but you can’t make it fast. By making a big batch and freezing it, you will have it available whenever you need it. Celery leaves are a critical component of vegetable broth.
Trim the tops off 1 or more leek and 1 head of celery. Reserve.
Chop 1 leek, 3 carrots and 3 celery stalks, then saute in 2 T. olive oil in a large soup pot until tender (you can skip the step of sauteing the vegetables, although the broth will be less rich).
Add 12 C. of water to the pot and add the leek and celery tops, along with 1 bay leaf, 12 whole peppercorns, 3 whole garlic cloves,
and 1 T. herbs de Provence or a mixture of basil, thyme, rosemary and sage.
For a non-vegetarian broth, you can of course also add poultry or meat bones, preferably cooked. For a seafood broth, add crab or shrimp shells or fish bones.
Simmer the broth (don’t boil it) at least 3 hours but preferably all day (or night, in a slow-cooker). Strain the broth to remove all of the solids, then freeze in 1 quart mason jars or plastic containers. Make sure to leave the top quarter of the container empty as the broth will expand as it freezes.