1 Rinse carrots, celery and fennel. Remove strings from celery if desired. Coarsely chop vegetables. Rinse tomatoes and coarsely chop.
2 Without peeling, halve onions. Peel and crush the garlic with the flat side of a chef's knife.
3 Heat olive oil in a large pot. Sauté fennel, carrots, celery, tomatoes, onions and garlic over low heat, stirring frequently, until softened, 8 to 10 minutes.
4 Add 4 liters (approximately 4 quarts) of water and bring to a boil.
5 Skim off any foam from surface of broth as necessary.
6 Rinse basil and shake dry. Add to pot, along with peppercorns, saffron and bay leaves. Cover and cook over medium heat until broth is flavorful, about 1 hour.
7 Strain broth through a fine sieve into another pot. Cook over high heat until liquid has reduced to about 1200 ml (approximately 5 cups). Use immediately, or let cool, refrigerate in an airtight container and use within 3 days.
8 To freeze: Using a funnel, pour the cooled broth into freezer bags, seal tightly and freeze. Use within 6 months.
9 Tip: To preserve the broth for longer, you will need to use a pressure canner and process jars according to manufacturer's instructions, or visit http://nchfp.uga.edu/.