Heat the olive oil in a large pot over medium-high heat, then add the chopped onion and sauté for about 5 minutes until softened, stirring occasionally.
Add the grated ginger, minced garlic, and Thai red curry paste to the pot and cook while stirring for about 30 seconds until fragrant.
Pour in the chicken or vegetable broth, water, and lime juice. Add the uncooked rice noodles and increase heat to high to bring the mixture to a gentle boil.
Stir in the coconut milk and shredded cooked chicken, reduce heat to medium-low, and simmer for 10 minutes so the flavors meld and the noodles soften.
Stir in the torn basil, chopped cilantro, and chopped scallions. Season with salt and pepper to taste.
Serve immediately with lime wedges on the side; add more broth if leftovers become too thick when reheating.
