Tomatoes are not the only vegetable to be used in sauces for pasta. Many others play an important part, either as a main ingredient or in a more minor role. Dried vegetables, such as porcini mushrooms, peppers and tomatoes, are used almost as often as fresh; valued for the intense flavour they impart to sauces and soups.
Fresh eggplant is used as a main ingredient in many pasta sauces, especially in southern Italy, Sicily and Sardinia. Dried eggplant is not used as a substitute for fresh, but is added to fresh vegetables for its characteristic earthy flavor and meaty texture. Sold in cellophane packages, they are thin slices of eggplant that have been dried in the sun, and are a good pantry item, in that you can use as few or as many as you Iike. They need to be rehydrated in boiling water with a splash of white wine vinegar for 2 minutes before use, then drained and dried. They can then be snipped into strips and either added immediately to a simmering pasta sauce or fried first in olive oil.
Crushed, sliced and chopped garlic is used in many pasta sauces, but especially in those from the south of Italy, and whole garlic cloves are sometimes fried in olive oil at the beginning of cooking, then removed to leave behind a subtly flavored base for a sauce. One famous Roman pasta dish, Spaghetti Aglio e Olio, holds garlic in such high esteem that the sauce contains only two ingredients—garlic and olive oil—and in Rome they maintain it is the best cure for a hangover. The best Italian garlic is pink or purple tinged, with plump juicy cloves. In spring and early summer you can buy it fresh at some greengrocers and Italian markets. This is the newly picked garlic that is sweet, moist and mild. As it dries out it becomes more pungent, so you need to adjust quantities accordingly. Buy garlic little and often so it neither sprouts green shoots nor becomes papery and dry.
Sun-dried red peppers are sold in cellophane packets. They resemble sun-dried tomatoes, but their flavor is more peppery and piquant. They are used in the same way as tomatoes, to add a firm meaty bite to sauces and soups, especially those made with vegetables. Before use they should be rinsed under the cold tap, then dried and cut into thin strips or chopped. Roasted peppers can be bought loose or in jars, packed in olive oil or brine. Although you can easily roast fresh peppers yourself when you need them, it is handy to keep a jar of commercially roasted peppers in the refrigerator. Just one piece of roasted pepper, sliced or chopped, will add a wonderful smoky flavor to pasta sauces, salads and soups. The best ones come from Italian markets where the peppers are grilled by hand and sold loose in extra virgin olive oil.
Porcini mushrooms (Funghi porcini)
Dried porcini (boletus edulis) are invaluable for the intense, musky aroma and flavor they impart to pasta sauces and soups. Italians use them all year round, not as a substitute for fresh porcini, but as a valued ingredient in its own right A few dried porcini added to ordinary fresh mushrooms, for example, will give them the flavor of wild mushrooms. Don't buy cheap porcini, but look for packets containing large pale-colored pieces. Although they will seem expensive, a little goes a long way, and 15-25g/1/2–loz is the most you will need in a recipe that serves 4-6 people. Before use, dried porcini must be reconstituted in warm water for 15-20 minutes. Drain, rinse and squeeze dry, then slice or chop as required. Don't throw the soaking liquid away. Strain it to remove any grit and use it in soups and stocks, or add it to the water when cooking pasta to impart a mushroomy flavor—this is especially effective with fresh pasta.
In summer, when fresh Italian plum tomatoes are ripe and full of flavor, it is wonderful to use these for sauce making, but at other times of the year you will get a much better flavor and color by using preserved tomatoes. There are plenty of excellent tomato products to choose from, most of which come from southern Italy, where the hot sun ripens the tomatoes on the vine to an incomparable flavor. Canned peeled plum tomatoes (pomodori pelati) come whole and chopped. Don't buy cheap brands; instead, opt for the top-quality Italian brands, especially those that identify the tomatoes as San Marzano on the label. If you ask at your local Italian market, they will give you good advice. Plain chopped tomatoes are a good buy because they save you from having to chop them yourself, but they are slightly more expensive. If they are labeled polpa di pomodoro, they are likely to be very finely chopped or even crushed. Flavorings, such as garlic and herbs, should be added fresh, so don't buy chopped canned tomatoes containing these. Filetti di pomodoro are sold in jars at good Italian markets and specialty food stores. These are plum tomatoes that have been halved or quartered and bottled al naturale in water and salt. They are about the nearest thing you can get to bottling tomatoes yourself at home, which Italians do in summer to preserve surplus tomatoes for winter use. Crushed tomatoes come in many guises, and are a real boon for sauce making because they take all the hard work out of peeling, seeding and chopping. They are plum tomatoes that have been mechanically peeled and crushed, then sieved to remove the seeds. You can choose from passata, which is quite smooth, to polpa and sugocasa, which are quite chunky.
Bottles and jars of these products are good in that they allow you to see what you are buying. Cartons of very smooth passata take up less room and are lighter to carry; they are very popular with Italian cooks for making almost instant sauces.
Sun-dried tomatoes (pomodori secchi) are sold in two different forms as dry pieces and in oil. Both types are piquant in flavor, but the dry pieces have a chewier texture than those in oil. Dried tomatoes are sold in cellophane packages and can be snipped directly into a long-cooking pasta sauce to intensify its tomato flavor, but generally they are best if softened in hot water for 2-3 hours before use. Sun-dried tomatoes in oil are sold in jars and can also be bought loose at some markets. For the best flavor, buy the ones in olive oil. They are soft and juicy and can be used as they are, either sliced or chopped, in sauces and salads.
Sun-dried tomato paste is a thick mixture of sun-dried tomatoes and olive oil. It can be used on its own as a quick sauce for pasta or added by the spoonful to tomato sauces to color and enrich them. Although thick in texture, the flavor of sun-dried tomato paste is sweet and mild compared with tomato paste, and the color is paler.
Tomato paste or concentrate (concentrate di pomodoro) is a very strong, thick paste made commercially from tomatoes, salt and citric acid. You can buy it in tubes, jars or cans, and its strength varies according to the manufacturer.
Get to know the brand you like because some are quite bitter and sharp, and can overwhelm other flavors in a sauce. Only use tomato paste in small amounts or it may make a dish too acidic. A way to counteract acidity is to add a pinch or two or a lump of sugar.