1. If using rice noodles, place in hot water to soak; soak for 15 minutes and drain; set aside.

2. In a large saucepan, bring chicken broth, onion, garlic, ginger, star anise, cinnamon stick, and brown sugar to a boil over medium-high heat. Reduce heat to a simmer and cook for 15 minutes. Add chicken and simmer until cooked through, 10 to 15 minutes. Carefully skim surface of any impurities and discard. Remove chicken from liquid and cut into bite-size pieces; set aside, reserving liquid.

3. If using rice noodles, bring a large pot of salted water to a boil. Add noodles and cook, stirring, for 45 seconds. Drain and rinse with cold water. Transfer noodles or pasta to a large serving bowl; toss with vegetable oil and set aside.

4. Fill a glass halfway with water and arrange herbs like a flower arrangement; set aside. Place bean sprouts, scallions, carrots, chile, lime wedges, and shallots each in individual small serving bowls. Set aside.

5. Return chicken cooking liquid to a simmer; stir in fish sauce and lime juice and season with salt and pepper. Strain broth into a teapot and keep any remaining broth heated on the stove. Fill serving bowls as desired with chicken, noodles, herbs, bean sprouts, scallions, carrots, lime wedges, and shallots; add hot broth and garnish as desired with fish sauce, chile sauce, and hoisin sauce. Serve immediately.