In a pot, bring enough water to cover noodles to a boil. Add noodles and blanch for about 1 minute. Drain and rinse in cold water.
In a pan over medium heat, heat about 1 tablespoon oil. Add liver and cook until just about done. Remove from pan and keep warm.
In a large pot over medium heat,, heat remaining 1 tablespoon oil. Add onions and garlic and cook until softened.
Add chicken and cook until lightly browned.
Add fish sauce and cook, stirring occasionally, for another 1 minute.
Add about 8 cups of water and bring to a boil.
Lower heat, cover, and simmer until chicken is cooked through.
Add noodles and cook for about 1 to 2 minutes or until half-cooked.
Add crab and corn soup mix and stir to dissolve. Season with salt and pepper to taste.
Add liver and cook for about 1 to 2 minutes.
Add carrots and cook for about 1 minute. Add napa cabbage and continue to cook for about 1 minute or until vegetables are tender yet crisp.
In a small bowl, combine corn starch and ¼ cup cold water and stir to dissolve. Add to the pot, stirring to combine. Continue to cook for until slightly thickened.
Add eggs slowly in a thin stream and allow to slightly set before stirring. Serve hot.