Heat oil in a large pot or deep skillet over medium-low heat. Add onions and minced garlic. Cook until onions are fragrant and softened.
Add chicken to the pot and cook for 2-3 minutes, allowing it to brown slightly. Stir in the curry powder and paste, and cook for an additional 3-5 minutes.
Pour in coconut milk and simmer for 15-20 minutes, or until the chicken is fully cooked.
Add the water or chicken stock, and simmer until the curry reaches the desired consistency.
Stir in the brown sugar, fish sauce, and lime juice. Taste and season with additional salt if desired.
Top with fresh cilantro, serve over cooked rice.
