Fuchsia Dunlop's recipe for Gong Bao Ji Ding is online here:
and it shows off the flavor/sensation of the peppercorns nicely. However, I would recommend toasting and grinding them, as opposed to leaving them whole as the recipe calls for. That distributes them more evenly throughout the dish, which I find preferable; the whole ones can be a bit much, flavor-wise. Also, as mentioned above, you may want to scale back the quantity a bit until you see how strong yours are.
While they add a glorious complexity to any number of meat and vegetable stir-fries (the Fuschia Dunlop threads might be a good place to start looking), to get a clear idea of their flavour and, as WChopper notes, peculiar sensation, I'd suggest a simple salad from Irene Kuo's excellent (and probably OOP) The Key to Chinese Cooking.
Place 4 cups shredded napa cabbage, 1 cup shredded daikon radish, 1½ teaspoons salt and a generous 1/2 teaspoon toasted and crushed Szechuan peppercorns.in a bowl. Toss well. Cover and refrigerate for 4-6 hours, turning the mixture from time to time. To serve, transfer to a colander and let the liquid drain off. Toss with 2 tablespoons chopped cilantro and 2 tablespoons toasted sesame oil or, for a more fiery dish, a mixture of sesame oil and chile oil or chile paste.
Baesook (Korean Peppercorn Pear)
3 Nashi (Asian) pears
3 tablespoons sugar
5 cups water
Wash the pears in cold water, peel, and cut into quarters.
Remove and discard core sections, then trim all sharp edges.
Push 3 or four peppercorns into the surface or each pear section just far enough that they do not fall out.
Put sugar and water into a pan and bring to a full boil over high heat.
Reduce heat to medium low and add the pear sections.
Cook for 10 minutes.
Remove from heat and let cool.
Transfer liquid and pear sections to a bowl or jar and refrigerate.
Serve cold (2 or 3 pear sections covered with juice) in small bowls.
I only use a few at a time (mine are potent -- thanks penzey's!).
First, toast them in a dry pan. When you can smell them, they're done (they don't take long). Then grind them in a mortar & pestle. At this point, you can pretty much anything with them (but don't touch your eyes or rub your nose).
I like to use the ground toasted peppercorns as part of a rub for chicken or fish, or as part of a seasoning for tofu & veg. If you're stewing something, add a few whole toasted ones to the pot as well. yum!
It's good in ma po tofu but as a word of caution before you get started, it has a very distinctive and unusual flavor. It almost numbs your lips and tongue. After eating a few bites of a dish I had over-seasoned with it, it felt like there were millions of antennae inside my mouth quivering and buzzing (I know that sounds very weird, it's difficult to describe). Long story short, use it cautiously at first until you figure out how potent it is and how much you like in a dish