Despite their most popular name, Szechuan peppercorns (aka flower pepper, fagara) aren’t actually peppercorns, but come from a different variety of plant entirely. One of the central spices in Chinese five spice powder, Szechuan peppercorns tingle the mouth with an almost citrus-like flavor. Those looking to experience a more powerful version of this tingling should try Sechuan Buttons.
 
As one might expect given their origin, Szechuan peppercorns are an integral part of fiery Szechuan Chinese food, not because they are spicy, but because they work extremely well with hotter spices.

Because of their reputation for carrying a plant illness judged to be harmful to American agriculture (a problem that has now been solved through careful irradiation) Szechuan peppercorns were impossible to find in the United States until a few years ago.

Store Szechuan peppercorns in their pouch or jar in a cool, dark cupboard. If grinding, do so just prior to use as pre-ground spices lose flavor and aroma over time.

Szechuan peppercorns are most often paired with star anise, and ginger. Though often toasted lightly before being ground, they can burn easily (not unlike normal peppercorns) and are thus usually added near the end of the cooking process. For a traditional taste of Tibet, pair them with yak meat, garlic, ginger, and onion.

How to Grind Whole Spices
Spice Recipes