How to Make Vegetable Stock

1. Stage

Rehydrate dried mushrooms: Place the dried mushrooms in a large bowl and pour 1 quart of boiling water over them. Set aside.

2. Stage

Brown the onions, celery, carrots, fennel: Heat the olive oil over high heat in a large stockpot. Add the chopped onions, celery, carrots, and fennel (if using) and stir to coat. Sprinkle with salt. Cook over high heat for several minutes, stirring only occasionally. Given that there are so many vegetables, and they have a high moisture content, it may take more heat and longer time to brown than you would expect. Cook until the vegetables begin to brown.

3. Stage

Add garlic and tomato paste: Add the garlic and tomato paste and stir to combine. Cook, stirring often, for 2-3 minutes, or until the tomato paste begins to turn a rusty color.

4. Stage

Add the mushrooms and their soaking water, the rosemary, thyme, onion skins (if using), peppercorns, bay leaves, parsley and 4 additional quarts of water: Bring to a simmer and then drop the heat until you just get a bare simmer. The surface of the stock should just barely be bubbling. Cook for 1 1/2 hours.

5. Stage

Strain the stock: Using a spider skimmer or slotted spoon, remove all the big pieces of vegetable and mushroom. Discard or compost. Set up a large bowl or pot with a sieve set over it. Line the sieve with a paper towel or coffee filter and pour the stock through it. When you have about half the stock poured through, stop, let what's in the strainer filter through, and change the paper towel; the old one will be gunked up with debris. Filter the rest of the stock.

6. Stage

Pour into jars and chill or freeze: To store, pour into glass jars and refrigerate for up to a week, or freeze. If you freeze in glass jars, leave at least an inch and a half of headroom so the stock can expand without breaking the glass of the jar.