Heat the vegetable oil in a large pot over medium heat. Add the chopped onion and sauté until soft, about 5 minutes.
Stir in the minced garlic and ginger and cook for another minute until fragrant.
Add the red curry paste and stir well to coat the onions, cooking for about 2 minutes.
Pour in the coconut milk and broth, stirring to combine. Bring the mixture to a gentle simmer.
Add the soy sauce, lime juice, mushrooms, bell pepper, and carrots. Cook for about 10 minutes until the vegetables are tender.
In the meantime, cook the rice noodles according to package instructions. Once cooked, drain and set aside.
Once the soup is ready, add the cooked rice noodles directly to the pot and stir to combine.
Taste and adjust seasoning if necessary.
Serve hot, garnished with fresh cilantro and lime wedges on the side.