Tamarind

The tart fruit of this evergreen tree is what we use, extracting its acidity. When fresh, the beanlike pods have an olive-green, tough, hide-like skin. When dried, the skin becomes brittle and greenish brown. Inside is the chocolate-colored pulp that shrouds the hard, dark brown seeds. Indian and Southeast Asian grocery stores carry tamarind in two forms: blocks of dried tamarind pulp (with or without seeds) and jars of tamarind paste or concentrate.

To create tamarind juice from the block form, soak a walnut-size chunk of the dried pulp in ½ cup warm water; this yields the same tartness as 1 teaspoon tamarind paste or concentrate dissolved in ½ cup water. After softening the pulp in water, break it up with your fingers; then mash it to release the tart brown juices while you loosen the intertwined pulp. Continue to soak and mash it until the liquid has a cloudy, muddy-brown appearance. Pour the liquid and pulp through a fine-mesh strainer placed over a small stainless steel, plastic, or glass bowl. (The highly acidic tamarind will react with metals like copper, iron, and tin, resulting in a metallic taste.) Mash and push the pulp through the strainer, and use the juice to sour curries. The pulp and its fibers may be used for a second, albeit weaker, extraction. As an added benefit, because of its high acidity, you can use the tamarind pulp to touch up polished brass and copper tchotchkes with pleasing results.