Fresh tomatoes are a delicious source of vitamin C, but recent findings attribute an even more important nutritional asset to this vegetable: It is one of the best sources of lycopene, a carotenoid with cancer fighting properties. Preliminary research suggests that lycopene may fight heart disease as well. The British eat a lot of tomatoes in processed form, as sauce on pasta or pizza, in soups, stews, and chilies, and as tomato ketchup, and as it turns out, this is one case where a vegetable is of greater value cooked than it is raw: Tomatoes contain a lot of water, so they become more concentrated as the water evaporates during cooking. The result is that a 110g of cooked tomatoes, in the form of sauce or paste, for instance, is a far more concentrated source of lycopene than a 110g of fresh tomatoes. And your body absorbs more lycopene from cooked or processed tomatoes, especially when the tomatoes are cooked with a little oil, as they often are. (Serving raw tomatoes with a drizzle of olive oil, for instance, also enhances lycopene absorption).

Varieties
Cherry tomatoes: Round and bite sized, these tomatoes are often served in salads and as garnishes. Their skin may be red or yellow.

Plum tomatoes: Also known as Italian or Roma tomatoes, generally found canned in the UK unless you grow them yourself which is well worth the effort, these are small and egg shaped. In general, they are meatier and less juicy than salad tomatoes, and so are ideal for making sauces and adding to other cooked foods.

Salad (round) tomatoes: These large, rounded varieties include round globe types commonly found in most supermarkets as well as the flatter beefsteak tomatoes (prized by competition gardeners, but not as tasty).

Heritage tomatoes: Some growers are now raising old varieties of tomatoes with intriguing shapes, variegated colours, and unusual flavours. Look for them at farmer's markets and gourmet shops during the tomato season.

Sun-dried tomatoes: These are plum tomatoes that have been dehydrated to preserve them and intensify their flavour. They are sold packed in oil or dry. The tomatoes that are not packed in oil are usually reconstituted by soaking them in hot water before using them in cooking.

Buying
From a nutritional point of view, the redder, the better. Ripe, in season tomatoes have as much lycopene gram for gram as canned products (although you won't absorb as much if you eat them raw.)

Never buy tomatoes from a refrigerated display; the cold damages them. Tomatoes displayed loose are easier to evaluate than those that are packed in boxes. Look for plump, heavy tomatoes with smooth skins. They should be free of bruises, blemishes, or deep cracks, although fine cracks at the stem ends of ripe tomatoes do not affect flavour. If greenhouse tomatoes still have their leaves, check that they are fresh and green.

Ripe tomatoes are fragrant, but even mature green ones should have a mild fragrance that promises future ripeness. If they have no aroma at all, the tomatoes were probably picked when immature, and will never ripen. Fully ripe tomatoes are soft and yielding to the touch; buy them only if you plan to use them immediately. Overripe tomatoes, provided they are not mouldy or rotting, are perfect for making sauces and even briefly cooking fresh tomatoes releases their lycopene. Choose whatever size tomatoes are appropriate for your intended use; size has no bearing on the vegetable's flavour, texture, or quality.

Storage
Room temperature (above 55°F) is best for storing tomatoes; don't refrigerate them. Place under ripe tomatoes in a paper bag with an apple or banana; the ethylene gas given off by the fruit will hasten the ripening process. Keep the tomatoes out of sunlight, they will overheat and ripen unevenly, and arrange them in the bag stem-side up to prevent bruising. Once the tomatoes are red and yield to the touch, they will keep for a day or two at room temperature. Should you need to keep them longer, refrigerate them; if they'll fit, place them in the butter compartment, which is the warmest part of the refrigerator. For full flavour, let the tomatoes come back to room temperature before you serve them.

Chopped tomatoes may be frozen for use in sauces or other cooked dishes. Tomato sauce also freezes well. When you have a plentiful supply of perfectly ripe or over ripe tomatoes, cook a batch of a basic sauce and freeze it for later use; use individual containers that hold the right amount of sauce for one meal.

Preparation
Wash tomatoes gently in cold water before serving them. To cut tomato slices for a salad or sandwich, stand the tomato upright and cut from top to bottom, the slices will retain their juices better than slices cut from side to side. Add sliced tomatoes to salads and sandwiches at the last minute because they begin to release their juices as soon as they are cut; contact with salty condiments or dressings will draw out more juice.

To remove excessive seeds or juice, cut the tomato in half crosswise, then hold each half cut-side down and squeeze it gently (you can sieve the juice and drink it). If you need very well drained tomato halves (for a stuffed tomato recipe, for instance), salt them lightly, then place them, with the cut-side down, on several layers of paper towel.

When a recipe calls for peeled tomatoes, drop them into a bowl of boiling water and blanch for 15 to 30 seconds (the harder the tomato, the more time it requires). Remove the tomatoes from the bowl with a slotted spoon and cool them briefly under cold running water. The skin can then be pulled off easily, using a paring knife. You can also spear tomatoes individually on a cooking fork and turn them slowly over a gas flame until the skin splits and can be pulled off. Or, you can loosen the peel in a microwave oven by heating it for 15 seconds on high power.