Chop all the vegetables into smaller pieces.
Put them in a large pot/sauté pan with the oil.
Sauté/heat them for about 10 minutes, until they get a little color.
Add water, peppercorns, bay leaves, and herbs.
Bring to a boil and then let simmer for about 1 hour.
Remove all the ingredients from the stock, which is easiest done by first pouring the liquid through a coarse-meshed sieve and then a fine-meshed sieve.
I usually boil it down a bit more afterward, often for another 15-30 minutes.
The stock is now ready to use.
It is freezer-friendly, so it is a good idea to let it cool down and pour it into either smaller containers/bags or even ice cube bags/trays.