A Dark Vegetable Broth is similar BUT - take the time,
3 - 4 cups of carrots
2 - 3 cups of celery
2 cups of leek - these are nice to have - but not required
4 cups of onions
2 tsp of dried thyme
a couple dried mushrooms (dark black/shitaki whatever you like, these are nice to have - but not required)
20 cups of water
The vegetables: washed, (not peeled,) and cut up / sliced to expose as much surface as possible without cutting them to mush. Take the paper skin part off of the onions and just slice them thinly.
With the leeks, I started out originally, just using the white/light green part, but recently have been using more and more of the dark green part. Particularly when making broth. The dried mushrooms add a lovely earthy taste,
In the case of the dark vegetable stock, I use two approaches depending upon the time that I have. The first is that I slice the onions rather than chunk them, and then cook them with some oil (use use an olive/canola blend) until they are a lovely Carmel colour. The second is that I will roast the vegetables in the oven until they start to get a good colour.
It is amazing the flavour difference if you take the time.
With everything in a stockpot, bring this to almost a boil (do not boil broths/stocks if at all possible) and simmer for one hour - longer if you want - but generally everything is cooked out by then.
Gently strain the broth into another pot (not down the sink) allowing as much of the moisture, still in the vegetables to drain out.
Portion this into 4 cup portions and freeze for up to three months. - just a general rule pf thumb that I have for most cooked food that I freeze.
I must make note of this site that I use to check out how long things are kept for.
Any thoughts on other uses for the green parts of leeks? - I just hate wasting things.