In a large pot, add chicken broth, ginger slices, red chilies, fish sauce, sugar, and bring to a gentle boil.
Add sliced chicken thighs or breasts, season with salt and pepper, and simmer until cooked through.
Meanwhile, cook pho noodles in a separate saucepan according to package instructions. Drain and set aside.
Once chicken is tender, remove it with tongs, slice if needed, and return to the broth.
Taste the broth and adjust seasoning with fish sauce, salt, or lime as desired.
In serving bowls, arrange noodles, ladle over hot broth, and top with chicken.
Garnish with bean sprouts, fresh herbs (mint, cilantro, Thai basil), and red chili slices.
Serve with lime wedges on the side for an extra burst of freshness.