_Frozen._—Cook frozen vegetables according to package directions.
For uniform cooking, thaw leafy vegetables just enough to separate
the leaves before you put them in boiling water. Partly thaw corn on
the cob before cooking it. If necessary, separate pieces of frozen
vegetables with a fork during cooking.
_Canned._—Commercially canned vegetables need reheating only. If liquid
is not served with the vegetable, save it for other uses. (See Ways to
Use Leftovers, p. 75.)
Unless you are absolutely sure home-canned vegetables have been
processed correctly, bring them to a rolling boil. Then cover and boil
for at least 10 minutes. Boil spinach and corn 20 minutes. If food
looks spoiled, foams, or has an off-odor during heating, destroy it.