Heat a large pot over medium/high heat. Add olive oil.
When olive oil is fragrant, add carrots, celery, and onion to the pot. Saute for 2-3 minutes.
Add mushrooms, garlic, and red pepper to the pot and saute veggies for an additional 2-3 minutes.
Next, add chicken broth, coconut milk, soy sauce, curry paste, ginger, and lemongrass to the pot and whisk everything together until combined.
Finally, place chicken breast into the pot and make sure it is submerged into the liquid. Bring to a boil.
Turn heat to low and simmer for 30 minutes.
While soup is simmering, prepare ramen noodles by following the instructions on the package.
When ramen noodles are done cooking, rinse with cold water and set aside.
Remove chicken breast from the pot, shred it, and add it right back into the pot.
Add lime slices and green onions to the soup.
If serving the soup immediately, add ramen noodles to the pot, bring soup to another boil, and then serve.
If meal prepping the soup or eating it later, store ramen noodles separate from the soup and combine the soup and noodles right before serving.