Singly and as a harmonious duo, these two herbs share a rich culinary heritage. Growing wild throughout the Mediterranean for centuries, rosemary and thyme have long been flavoring the cooking of Greece, Italy, France, and their neighbors. Today, these uplifting herbs from the mint family are grown in temperate climates around the globe and show up in everything— from meats to sweets.
Rosemary (Rosmarinus officinalis) is Latin for "dew of the sea," which refers to the herb's coastal habitat. Rosemary was used as far back as 500 B.C., mostly in potions and medicine. Ancients burned it as incense to purify the air and capitalized on its stimulating properties. Similarly, thyme (Thymus vulgaris) was used to heighten mental clarity and ward off evil.
Rosemary, with its pine scent, and common thyme, with its camphor notes, extend their magical qualities into the kitchen. Both herbs enhance numerous dishes—singly or in combination. In fact, the two marry well and are used together in such blends as herbes de Provence, which also employs marjoram, oregano, and savory. Working alone, rosemary pleasantly flavors a number of foods—from roast leg of lamb to focaccia. Its woodsy scent is softened by heat—whether on the grill, in the oven, or in the sauté pan. Fresh sprigs of rosemary make attractive skewers for kabobs.
Thyme, another universal herb, does well with many preparations, particularly slow-cooked foods that allow the heat to release the herb's aromas. Included here are stews, soups, and sauces, as well as roasted meats and fish. Thyme is also popular in Cajun cuisine, an indication of its French heritage, and can be found in spicy gumbos and classic jambalayas. A traditional bouquet garni—fresh thyme sprigs, parsley, and bay leaf tied together or placed in cheesecloth—flavors soups and other simmered foods.
Lemon thyme (T. citriodorus), which has a stronger citrus aroma, makes a refreshing herbal tea, and can be used in seafood and poultry dishes towards the end of cooking time. Lemon thyme also invigorates such fruits as oranges, pears, and figs.
Although fresh herbs provide the best flavor, dried rosemary and thyme leaves do retain much of their aroma. Crush dried herbs in the palm of your hand before using. When making substitutions, most recipes indicate using a smaller amount of dried herbs than fresh; when 1 tbsp. fresh thyme or rosemary is called for, it can be replaced by 1 tsp. dried (a 3:1 ratio).
Fresh rosemary and thyme are best kept wrapped in a moist paper towel and refrigerated in plastic bags. Properly stored, these fresh herbs can last a week to 10 days. Fresh thyme leaves can be frozen with water in ice-cube trays, ready to be plunged into a simmering soup or stew.
Herb-infused vinegars, butters, and oils are also smart ways to preserve fresh herbs. Rosemary, in combination with garlic in red wine vinegar, can dress braised white beans or simple salad greens. Butter whipped with shallots and thyme makes a tasty spread for rustic breads. Herb-infused oils are delicious as a dipping sauce for breads, in marinades for grilled fish or chicken, or tossed with pasta.
Fresh rosemary and thyme are available year round in bunches or by the pound. The dried forms are available either in ground or whole leaf form in jars or packs.