1 large onion, peeled and halved
2 medium carrots, peeled and cut into large pieces
3 stalks celery, cut in half
1 bay leaf
4 1/2 cups water
Add the onions, carrots, and celery to the pressure cooker pot. Add the peppercorns, bay leaf, and water to completely cover the vegetables. Close and lock the lid.
Select high pressure and 15 minutes cook time.
When the beep sounds, turn the pressure cooker off and use a natural pressure release.
Strain the stock through a fine mesh strainer. Store in the refrigerator for 2-3 days, or freeze for up to 3 months.