I like to save a bag of veggie scraps to throw in the stockpot. Certainly, not spoiled produce, but a few days old is fine. I use everything except carrot greens which contains some toxins. Just keep in mind that it will be a flavour meld, so if you add beets expect a pink and borscht-y broth. Experiment with different tastes. Root veggies can also add depth. I have kept them out of this recipe so it remains low carb.
3 organic carrots
3 sticks organic celery
1/2 organic white cabbage cut in pieces
5 cloves garlic chopped
2 onions chopped
1 bunch of scallions, chopped
Whatever leftover veggie pieces you have over the last couple days.
Herbs that you like (I use bay, parsley, fennel, and oregano. You may want to change it up if you are making an Asian inspired stock)
32 oz quality water plus more to keep the pot filled as it boils off.
Add all ingredients to a big soup pot with a good fitting lid. Boil on medium heat in the covered pot for around 1 hour. Taste and add more water. Adjust seasoning. If you would like a stronger flavour, add more water and more veggies. Cook for another half hour. Make sure the water level stays at the middle of the pot. If you are using a pressure cooker, bring it up to high pressure, cook for fifteen minutes, cool down, test taste and add more water. If necessary cook for ten more minutes. When your stock is done, let it cool, and strain out veggies. Sometimes I like to blend in the soft veggies like carrots and celery, so make a thicker stock. An immersion blender works well for this.
If you want to create a concentrated stock, put 8 oz into a small pot and boil it down to 4 oz. Use this to fill ice cube trays to freeze. Once frozen keep the cubes in a plastic bag in the freezer. Add these as needed into a sauce or a veggie stir fry. If you want to create a clear consume, wrap your herbs in a cheesecloth so they can be cleanly disposed of when you soup is complete.