Heat oil in a large skillet over medium-high heat. Sauté onion, bell peppers, garlic, and ginger until onion is translucent.
Add chicken to the skillet and stir to coat with the curry mixture. Pour in coconut milk, fish sauce, sugar, and lime juice.
Stir in basil leaves and chopped peanuts and let cook for a few more minutes. Adjust seasonings and add salt and pepper if preferred.