Chop the vegetables and set aside.
Heat a large stockpot over medium high heat. Add the olive oil, onions, celery, carrots and green onions and heat for 8-10 minutes, stirring frequently.
Add the garlic, parsley, thyme and bay leaves and heat for 2-3 minutes.
Add the peppercorns, salt and water and bring to a rapid boil.
Turn down the heat to medium low and let cook for 30 minutes, uncovered.
After 30 minutes, pour through a mesh sieve into a large glass bowl. Discard the solids or store for another use.
Store the stock for up to 3 days in the refrigerator or up to 6 months in the freezer.