Sichuan pepper (or Szechuan pepper, or Chinese prickly ash), is neither pepper nor exclusively from Sichuan province. There are a number of species in the genus Zanthoxylem that produce fruit that are commonly used for cooking; and it’s an important seasoning in food from Nepal to Japan (where it’s called sansho). The taste of sichuan pepper is characteristically numbing (in Chinese, it’s the ma in classic ma-la 麻辣, or numbing-spicy food). The flavour is often lemony, and even salty. There are a few things to consider when cooking with Sichuan pepper.
The useful part of the Sichuan pepper is the dried outside of the fruit (this is directly homologous to the peel of an orange). In Japanese cooking, both the leaves and the fruit are commonly used. The little fruits split open, to drop their single, shiny, black seed. But when you buy them, many fruits will still contain the seed. This is a problem, because when you grind the Sichuan pepper, the seeds with also crush. They add nothing to the flavour, but give food a nasty, gritty, almost sandy texture.
So, before you use the pepper, try and remove whatever seeds you can — with your fingers, or crush them with the flat of a knife blade, and remove the bits of black seed. Usually, then, the seeds should be toasted and ground, or added whole (often into hot oil).
Sichuan pepper is important in five-spice; in Sichuan food like ma-po tofu, fish-fragrant pork, and water boiled beef; in Nepalese food like momo; and in the addictive Lao Gan Ma chili sauces (we don’t often recommend bottled sauces, but Lao Gan Ma is very, very good).
When you’re buying Sichuan pepper, there is an astonishingly large amount of variation among brands in quality and taste. Some batches we’ve had tasted like pretty much nothing (except for gritty sand); while others are more piney, and others more lemony. Look for brightly coloured pinkish or reddish fruit, and a minimum of seeds. Then, you’ll just have to taste it to make sure it’s good.
Take a couple fruits, and chew on them slowly. After about 30 seconds, you’ll get the aroma — it should be vivid, and refreshing. Next, a weird, numbing feeling will come over your mouth. It’s not entirely pleasant, but it is interesting. And after a while, your tongue will feel tingly, and tastes will be off (water will taste salty) for a minute or two. If you don’t feel this, the pepper is not good. Throw it out, and get a different batch.
Botany and cultivation:
Sichuan pepper is not related to pepper at all. It’s in the same family, Rutaceae, as citrus and rue. In fact, once you get familiar with the tingliness of Sichuan pepper, you’ll notice that the raw peel of citrus fruit gives a similar sensation.
It grows pretty easily, almost anywhere that’s not too cold (by which I mean Canada) — there’s a particularly nice specimen just outside the UCLA arboretum. It makes nice bonsai.