- Pour just enough water into the stockpot to start the onions cooking.
- Add the onion, leek top, garlic, shiitake mushrooms, and salt.
- Give the vegetables a stir, then cover the pot and cook gently over medium heat for 15 minutes.
- Add the remaining ingredients and cover with 9 cups cold water.
- Bring the stock to a boil, then simmer, uncovered, for 1 hour.
- Pour the stock through a strainer, pressing as much liquid as you can from the vegetables, then discard them.