Heat a large pot over medium heat.
Add the green curry paste and sauté until fragrant.
Stir in the chicken (or tofu) and cook until browned.
Pour in the coconut milk and broth, stirring to combine.
Bring the mixture to a simmer.
Add the sliced bell peppers, zucchini, and eggplant.
Stir in the fish sauce and brown sugar.
Simmer for 15-20 minutes until vegetables are tender.
Taste and adjust seasoning if needed.
Serve hot, garnished with fresh basil leaves.