Gather all your ingredients and prep your workspace. Peel and chop carrots, slice bell peppers, chop onions, mince garlic, and grate fresh ginger. Bruise the lemongrass stalks to release their aroma.
Heat the large pot over medium heat, add a splash of oil, and sauté the chopped onion until it becomes translucent and fragrant, about 5 minutes.
Add the minced garlic, grated ginger, and bruised lemongrass to the pot. Cook for about 2 minutes until the mixture is fragrant and aromatic.
Stir in the chopped carrots and sliced bell peppers, and sauté for another 8 minutes until they start to soften, their colors brightening and textures becoming tender.
Pour in the chicken broth and bring the mixture to a gentle simmer. Skim off any foam that rises to the surface to keep the broth clear.
Add the shredded cooked chicken to the broth, squeeze in the lemon juice, and season with salt and pepper. Stir to combine.
Let the soup simmer uncovered for about 20 minutes, stirring occasionally, until all flavors meld and vegetables are tender but not mushy.
Taste the broth and adjust the seasoning with more salt, pepper, or lemon juice if needed, for brightness and balance.
Remove the lemongrass stalks from the soup, discard, and give the broth a final stir. Let it rest for 5 minutes to deepen the flavors.
Serve the hot soup in bowls, garnished with additional fresh herbs if desired, and enjoy the bright, aromatic flavors with tender vegetables and shredded chicken.
