Chicken stock recipe

I have a big freezer bag I fill up with chicken bones, celery tops, extra herbs, onion tops and carrot peels. When the bag is full, I make this delicious chicken stock. 

The bone broth is so much better than store-bought that I won't even bother making soups or risotto unless I have some on hand. 

Chicken stock recipe:
- Bones from 3-4 chickens
- 2 large onions, roughly chopped (it's ok to leave the skins on)
- 3 carrots, no need to peel
- 1 clove garlic, sliced in half (it's ok to leave the skins on)
- 3 stalks of celery
- 1 TB salt
- 1/2 tsp ground pepper
- 1/2 tsp dried thyme (or use 8 sprigs of fresh)
- 1/2 tsp dried dill (or use 10 sprigs of fresh)
- 10 sprigs fresh parsley, put in whole
- 1/2 tsp vinegar
- Water – enough to fill up the stock pot

Directions: Put all ingredients in a stock pot and bring to a boil. Boil uncovered for several hours over medium heat until at least 1/3 of the liquid has evaporated. Strain, discard bones and solids and then store in freezer containers. 

I use it solely for the flavor, but evidently bone broth has some nutritional benefits. It's rumored to be high in calcium and protein too. I've read adding a splash of vinegar helps extract more collagen from the bones...though I don't know if it's true.