From America's Test Kitchen From March 2, 2013: The Kitchen Sisters Unplugged: America's Hidden Food Stories.
Since tolerance for spiciness can vary, we’ve kept our recipe relatively mild. Sweetness without sufficient heat can become cloying, so we also cut back the sugar. For a very mild version of the dish, remove the seeds and ribs from the chiles. If fresh Thai chiles are unavailable, substitute 2 serranos or 1 medium jalapeño. In Thailand, crushed red pepper and sugar are passed at the table, along with extra fish sauce and white vinegar, so the dish can be adjusted to suit individual taste. Serve with steamed rice and vegetables, if desired.