Combine pork, 1 tablespoon soy sauce, rice wine and pinch of white pepper in small bowl; stir well and set aside.
Whisk peanut butter, oyster sauce, vinegar, pinch of white pepper and remaining 2 tablespoons soy sauce together in medium bowl. Whisk in broth and set aside.
Bring 4 quarts water to boil in large pot.
Meanwhile, heat 12-inch skillet over high heat, add vegetable oil and swirl to coat. Add pork mixture and cook, breaking into small pieces with wooden spoon, until well browned, about 5 minutes.
Add garlic, ginger and pepper flakes and cook, stirring constantly, until fragrant, about 1 minute. Add peanut butter mixture and bring to boil, whisking to combine, then reduce heat to medium-low and simmer, stirring occasionally, until flavors have blended, abut 3 minutes. Stir in sesame oil.
While sauce simmers, add noodles to boiling water and cook until tender, 4 to 5 minutes. Drain noodles and divide evenly among bowls. Ladle sauce over noodles and sprinkle with bean sprouts, green onions and peppercorns. Serve immediately.