Dice the scallions into small rounds and grate the peeled ginger, then place them in a heat-proof bowl. Add sesame oil, salt, white pepper, and Sichuan peppercorn powder (if using).
In a small saucepan, heat the avocado oil over medium-low heat for about 7–8 minutes until it simmers—test by inserting a dry chopstick to see if bubbles form. Carefully pour the hot oil over the aromatics, allowing it to sizzle. Stir to combine and let the scallions soften for a few minutes.
Bring a large pot of water to boil. Follow the package instructions to boil the noodles. Drain well and divide them into 4 equal serving bowls.
Season serving bowls:
Add 2 tsp oyster sauce and 2 tsp black vinegar to each individual serving bowl.
Combine and serve:
Add the noodles and toss to combine then ladle a few tablespoons of scallion oil and sprinkle crispy shallots on top. Toss again. Serve right away.
Notes
Scallion sauce storage: You are likely to have extra leftover sauce. Once the sauce has cooled to room temperature, transfer it to an airtight glass container. Store in the fridge for up to 1 month, but for the freshest flavor, use it within the first 2 weeks.