The next time you’re cutting up vegetables, save the scraps in a plastic bag and freeze them for future use in a quick stock. Almost every part can be salvaged -- the tough outer leaves of artichokes, even the skin of onions. And make sure bits of the onion itself make it into the pot: The vegetable is the workhorse of soup bases. We like to use vegetable broth to poach fish. Trout, salmon, halibut, and cod all hold up nicely in the simmering broth.