Heat the oil in a wok or large, heavy skillet over high heat. Add the garlic, shallots, ginger, and chilis and saute until fragrant but not brown, about 30 seconds, stirring constantly.

Stir in the tamarind, fish sauce, and sugar and bring to a boil over medium heat. Reduce heat to medium low and simmer gently, uncovered, until thickened and the flavors are well blended, about 5 minutes. Remove from the heat and taste for seasoning, adding fish sauce or sugar (more) as necessary; the sauce should be highly seasoned. Stir in the cilantro (if using) and transfer the sauce to bowls and let come to room temperature. Serve immediately. Makes about 1 cup.

mouthpuckering tartness makes a nice counterpoint to the grilled fare of Southeast Asia. Serve this lively sauce with sate, but don't stop there. Grilled shrimp, chicken, pork, and even hamburgers shine in its presence.