Prep Potatoes: Peel the potatoes. Julienne them into thin, 2-inch matchsticks using a knife or mandoline.
Wash Starch: Immediately place the potato slivers into a large bowl of cold water. Swish, drain, and repeat 2-3 times, until the water is no longer cloudy. This is essential for a crunchy texture. Keep the potatoes submerged in fresh cold water.
Prep Other Veggies: Julienne the green and red bell peppers to match the potatoes. Chop the cilantro.
Make Dressing Base: In a large mixing bowl (the one you'll toss the salad in), combine the Chinkiang vinegar, light soy sauce, oyster sauce, sugar, and optional chicken bouillon powder.
Make Fragrant Oil: In a small, heat-proof bowl, add the white sesame seeds and Chinese chili powder. Set aside.
Infuse Oil: Add the neutral oil and Sichuan peppercorns to a small saucepan. Heat over medium-low heat for 2-3 minutes until fragrant. Strain the hot oil over the chili powder and sesame seeds (discard the peppercorns). It will sizzle and bloom.
Combine Dressing: Pour the sizzling fragrant oil mixture into the larger bowl containing the sauce base. Stir well to dissolve the sugar.
Blanch Vegetables: Bring a large pot of water to a rolling boil. Drain the potato slivers and add them, along with the bell pepper slivers, to the boiling water. Cook for 60-90 seconds *only*.
Shock: Immediately drain the vegetables and rinse them under cold running water to stop the cooking process. Drain *very* thoroughly, shaking off all excess water.
Toss and Serve: Add the well-drained potatoes and peppers to the large bowl with the dressing. Add the chopped cilantro. Toss well to combine. Serve immediately or chilled.