Differences in Puree

• Many home cooks in the U.S. think tomato puree is interchangeable as an ingredient with canned crushed tomatoes and tomato sauce, which are used most commonly in Italian-style dishes. In Indian cooking, tomato puree is made from raw tomatoes, not canned, and blended until smooth. The tomato puree is pourable and not too thick, and it's often used by the tablespoon to provide a smooth base to Indian dishes. No spices are in traditional Indian tomato puree, but traditionally, vinegar, salt and sugar are added to help preserve it.

Preparing and Par-Boiling

• Raw tomatoes fresh from your garden or grocery store are the most important ingredient for Indian tomato puree. Tomatoes are blanched before blending to preserve their bright color and facilitate easy skin removal. After rinsing, cut a shallow "X" into the ends of your tomatoes for even cooking and quick peeling. Bring enough water to cover the tomatoes to a roiling boil, and carefully drop in the fruit using a pair of kitchen tongs. Once the water returns to a boil, turn the heat down to medium-low and boil for 10 to 15 minutes until the skin starts to peel back.

Peeling and Processing

• Before handling, cool the tomatoes by transferring them to a bowl and covering them with cold tap water. The skins peel off easily; discard them or use them to flavor sambars, Indian hot and sour stews seasoned with tamarind paste or tomatoes. To make a smooth, thick tomato puree, remove the seeds by cutting the fruit in half and scooping them out before processing; leaving in the seeds adds liquid and a slight bitter flavor. Place the prepared tomatoes in a blender or food processor without water and whir until you achieve the desired smoothness.

Preserving and Storing

• Fresh tomato puree lasts for two to three days in the refrigerator. To increase its storage life, freeze the puree in zip-top style bags or ice cube trays for use in everyday Indian cooking. To increase refrigeration shelf-life, cook the puree with salt and equal amounts of vinegar and sugar -- about 1/4 teaspoon per 4 to 5 tomatoes -- and boil on the stove top until thick. Pour the puree into sterilized jars or containers. This is not the same process as canning, but puree cooked with a preservative and stored in an air-tight container keeps in a refrigerator for up to two weeks.

Fresh and Coarse Puree

• For a coarse tomato puree, the ingredient in some Indian dishes, the tomato is chopped into larger pieces. This kind of puree is made from raw, ripe tomatoes grated over the roughest part of a cheese grater. Slide the tomato along the grater until the skin grabs, and grate the tomato, allowing the juices to fall into a bowl. The skin will bunch up and collect in your hand; discard it. If the skin slides across the grater and doesn’t catch, slice off a small piece with a knife to help.