Do you need to buy specialty chile products for Asian dishes?
Without spicy chile heat, it's not kung pao (see related recipe). The recipes we consulted, however, offered little agreement about the best source of that heat. For the sake of convenience and simplicity, we immediately ruled out exotic chili sauces that can be had only in ethnic markets. Instead, we hit the supermarket up the street and picked up the most oft-repeated contenders, including whole dried chiles (the traditional choice), crushed red pepper flakes, fresh chiles, chili oil, and two popular and widely available Asian chili sauces, Sambal and Sriracha. Thus outfitted to heat things up, we returned to the test kitchen and conducted a side-by-side kung pao tasting.
The exact formula for Sambal, a chunky chili-garlic paste, varies from maker to maker. Ours was seasoned with salt, sugar, and rice vinegar. Smoother Sriracha is a popular Thai chili sauce, and ours was seasoned with salt, sugar, garlic, and fish extract. Both Sambal and Sriracha are common Asian table condiments, but tasters gave them thumbs-down in the kung pao because they lacked depth and tended to taste too salty. Chili oil was also passed by because the one we used, actually a chili-flavored sesame oil, was judged too mild, and it made the sauce a bit greasy. The fresh chiles—jalapenos, to be exact—provided sharp heat, but the tasters did not appreciate the distinct green, vegetal notes. Crushed red pepper flakes provided a bright, direct heat that was utterly acceptable, but the tasters' favorite by a long shot was the whole dried chiles, which infused the kung pao with a round, even spiciness that offered a deep, toasty, almost smoky dimension as well.
This finding, of course, begged the question of whether one particular type of dried chile would be best, as there are many varieties. With our sights set on relatively small chiles (large chiles simply looked wrong in the dish), We returned to the market and gathered six varieties, including an unnamed Asian specimen from the bulk bin, Japones, Arbol, Guajillo, Costeo, and Cascabel. Tasters strained to detect distinctions between them in our kung pao. We concluded that any small whole dried red chiles will do quite nicely.