I found this dressing at seriouseats.com.
Ingredients:
For the Seasoning Oil: 1 teaspoon whole Sichuan peppercorns, reddish husks only and stems and black seeds discarded 1 dried chile, stemmed or 1 teaspoon dried red pepper flakes 1 bay leaf 1/2 star anise pod 1 cup neutral-flavored oil, such as peanut, canola, soybean, or vegetable 1 green onion, ends trimmed cut into 1-inch segments 1/2 large shallot, thinly sliced 1/2-inch knob fresh ginger, peeled and sliced thinly into coins 4 medium cloves garlic, smashed For the Vinaigrette: 3 tablespoons Chinese light soy sauce 1 tablespoon granulated sugar 1 tablespoon Chinese Zhenjiang (black) vinegar 3 tablespoons Seasoning Oil
Preparation:
For the Seasoning Oil: In a small bowl, cover Sichuan peppercorns, dried chile, bay leaf, and star anise pod with cold water and soak for 5 minutes. Drain well.
In a small pot, combine oil, drained spices, scallion, shallot, ginger, and garlic. Set over low heat and cook until the scallions and garlic are gently frying and have turned an amber brown color, about 8 minutes. Remove from heat, strain into a heatproof container, and let cool; discard the solids. For the Vinaigrette: In a small bowl, whisk together soy sauce, sugar, black vinegar, and seasoning oil until sugar is dissolved. The final dressing will not remain emulsified, so mix or shake it just before using.