Place rice noodles in large bowl. Pour 4 cups boiling water over noodles and let soak until al dente, 5 to 7 minutes. Drain and run under cold water. Set aside.

In medium bowl, whisk together fish sauce, rice vinegar, peanut butter, brown sugar, and red pepper flakes; set aside.

In large wok over high heat, heat oil . Add garlic, ginger, and ¼ cup green onions and stir-fry until fragrant, 1 minute, then add eggs and cook, scrambling with wooden spoon, 2 minutes. Add 1½ cups bean sprouts, red peppers and stir-fry until crisp-tender, 3 minutes. Move bean sprouts and egg mixture to side of wok and add shrimp to other side; let cook for 5 minutes or until bright pink. Stir everything together and add sauce and the noodles. Gently toss mixture until noodles are heated through and sauce has thickened slightly.

Serve immediately, garnished with chopped peanuts, lime wedges, red pepper flakes, cilantro and remaining ½ cup bean sprouts.