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 and simmer until chicken is cooked through.
Add noodles and cook for about 3 to 5 minutes or until tender yet firm to bite.
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 1/4 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.