Heat about 4 quarts of water. Add peppercorn, bay leaves, some fennel seeds (optional). Add the vegetable scraps (or vegetables). Bring it to a boil.
Then lower the heat to a really low flame. Simmer it partly covered for about an hour.Use immediately or let it cool and store it in a jar to be either refrigerated (can be used for up to 3 days) or frozen (can be used up to a week)
Notes
Vegetable scraps or vegetables – Use very thoroughly cleaned vegetable scraps (or chopped vegetables). Any non-starchy vegetable scarps (or vegetables) would work. Generally scraps of onion, garlic, celery, and carrots in addition to some herbs work. But you can use anything, as long as it is non-starchy. You can also freeze the cleaned vegetable scraps for a couple of days and use it to make the stock.