Rough chop vegetables and place in food processor to only 1/2 full. Do in batches if processor is small. Pulse to get a nice fine dice. Don't go too far or you'll have a veggie soup!
In medium saucepan over MED heat, add celery seeds and pepper, toast for 1 min.
Add rest of ingredients, combine well and simmer on LOW heat, 10-12 min or until mixture thickens slightly. It will also thicken a bit after it cools.
Using a fine mesh sieve, BRIEFLY drain mixture of excess water. Don't leave mix in the sieve, you want a little water retention.
Chill and serve. Store in fridge up to two weeks but let's be honest, this won't last that long!