Heat the olive oil in a large pot over medium heat. Add the onion and sauté until translucent.
Stir in the garlic and ginger, cooking for another minute until fragrant.
Add the red bell pepper and cook for an additional 3-4 minutes until softened.
Pour in the coconut milk and broth, stirring to combine.
Bring the mixture to a simmer before adding the lime juice, fish sauce, and sugar.
Season the soup with salt and pepper to taste.
Gently add the fish pieces to the soup. Simmer for 5-7 minutes until the fish is cooked through.
Remove the pot from heat and stir in the fresh cilantro.
Serve the soup hot, garnished with lime wedges.