To make the vegetable stock, add the olive oil to a heavy-bottomed pan or stockpot over a medium heat. Add the onion, leek, carrot and fennel and sweat for 2-3 minutes, then add enough cold water ...
Put them in the freezer, and you can pull them out next time you want to have stock. The same goes for vegetable leftovers, such as broccoli stems (if you're not cooking them). When you pull the ...