In a large pot, bring 3 cups water to a boil with vinegar, agave, bay leaf, celery seeds, fennel seeds and salt.
Once brine is boiling, add vegetables and return to a boil. Remove from heat and allow vegetables and brine to cool to room temperature.
Strain mixture through a fine-mesh sieve, collecting liquid in a container below. Discard bay leaf and transfer pickled vegetables to 3 pint-size (500ml) sterilized glass jars with tightly fitting lids. Pour reserved vinegar mixture over vegetables. If liquid doesn't reach top of jars, add a little extra water or vinegar. The pickled vegetables will keep in the refrigerator for up to 2 weeks.
Adapted with permission from Eating in Color, by Frances Largeman-Roth. Stewart, Tabori & Chang; January 2014.