Heat 2 tablespoons of olive oil in a large pot over medium heat. Add the finely chopped onion and sauté for about 5 minutes until translucent.
Stir in grated fresh ginger, minced garlic, and Thai red curry paste. Cook until fragrant, about 30 seconds.
Pour in 4 cups of broth, 2 cups of water, and the juice of one lime. Bring to a gentle boil, then add 3.5 ounces of uncooked rice noodles. Boil for 3-4 minutes.
Reduce heat, stir in one can of coconut milk and 2 cups of shredded chicken. Let it simmer for 10 minutes.
Stir in fresh basil, cilantro, and scallions. Season with salt and pepper to taste.
Ladle the soup into bowls and serve immediately with lime wedges if desired.