Some vegetables preserve their flavor and texture after freezing; others don't. Salad vegetables like tomatoes, cucumbers and onions lose their crispness when they're frozen, although they're still suitable for flavoring soups and stews. Freezing doesn't improve vegetables, and may intensify any off-flavors that may be present, so always start with the freshest, highest quality produce available. Before freezing, vegetables must be blanched in either boiling water or steam for a short period to destroy active enzymes that can affect flavor. Broccoli, cauliflower, corn, peas, and several other vegetables require steam blanching, while boiling is recommended for most others. Blanching time varies from two to ten minutes, depending on the vegetable. You can find complete charts in many cookbooks. After blanching, cool the vegetables quickly in cold water, drain, and freeze immediately. Plastic bags with all the excess air squeezed out make excellent freezer containers. Label them with the name of the vegetable and the date and use within 3 to 6 months.