In a small skillet over medium heat, cook shallots in oil until brown and fragrant. Remove from heat and set aside.
Bring a large pot of water to a boil. Cook noodles in boiling water until just tender, 8 to 10 minutes; drain and rinse under cold water. Set aside.
Bring a small pot of water to a boil; have ready a bowl of ice water. Blanch bean sprouts by plunging them into boiling water for 1 minute, then into cold water. Drain and set aside.
In a large saucepan over medium heat, bring chicken broth to a simmer.
Divide noodles evenly between 6 bowls. Top with bean sprouts and shredded chicken. Pour the heated broth into the bowls. Drizzle with the shallot mixture and garnish with the green onion. Season with salt and pepper. Serve at once.
