Heat oil in a large pot over medium-low heat. Sauté the onion until softened. Add the chicken, carrots, and potatoes and cook briefly.

Stir in the ginger, garlic, and curry paste and sauté for 3 minutes until fragrant.

Add 1 1/2 cans of coconut milk. Mix the cornstarch into the remaining half can and add to the pot. Bring to a boil.

Reduce heat and simmer for 20-30 minutes until the chicken and potatoes are cooked through. Add water if needed to adjust consistency.

Stir in fish sauce, brown sugar, and lime juice. Simmer 5 more minutes. Serve over rice garnished with fresh cilantro.