Found the recipe below in a cook book "A New Way to Cook" which I modifed to make it vegetarian and simpler and also added celery because I was going grocery shopping and needed to clean out the residual produce tidbits in my fridge.

It works and tastes pretty good. I have started keeping leeks in my fridge on a regular basis because they really "mellow out" recipes. They are a bit expensive here in Houston now but I find them worth it.

I did do some approximation on the recipe below and not suprisingly they worked. The potato I used was large. Maybe the leeks too because it took more than 6 cups of cold water to cover the veggies.

I also modified the method of cooking. I put all ingredients in a slow cooker, setting low and cooked for 8 hours. I put this on when I was cleaning out my fridge to go grocery shopping.

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(This is mostly the way it was in the book except
for elimination of meet and addition of celery)

Leek Broth (or Vegetarian Stock)

3 medium leeks , trimmed, coarsely chopped and rinsed
1 small potato, (about 3 ounces, peeled and cut into chunks)
1 medium shallot (thinly sliced)
1 celery stalk/stick
2 teaspoons unsalted butter or extra-virgin olive oil
6 cups cold water
1/2 teaspoon kosher salt
1/4 teaspoon sugar

In a large heavy saucepan, combine all the ingredients. Bring to a boil over moderate heat, reduce the heat, and simmer until the liquid is reduced to 4 cups, about 45 minutes.

Straing the broth hrough a fine sieve set over a bowl, pressing on the vegetables to extract as much liquid as possible, discard the solids.

The broth can be refrigerated, covered, for about 4 days or frozen for up to 2 months.