Method
Heat the vegetable oil in a large skillet or wok over medium heat. Add the onion and red bell pepper, and sauté for 3-4 minutes until softened.
Stir in the green curry paste and cook for 1 minute, stirring constantly, until fragrant.
Pour in the coconut milk, fish sauce, and brown sugar. Stir well to combine and bring to a gentle simmer.
Add the fish pieces and zucchini to the skillet. Cook for 5-6 minutes, stirring occasionally, until the fish is opaque and cooked through.
Remove the skillet from heat and stir in the fresh basil and cilantro. Taste and adjust seasoning if needed.
Serve the curry hot with steamed rice and lime wedges on the side for squeezing over the dish.