A day before marinate chicken thighs with curry paste and leave in the fridge overnight.
Next day.
Heat half the oil in a large frying pan over medium heat. Cook the chicken in batches for a few minutes or until browned. Remove to a plate and leave aside.
Heat remaining oil in the same pan over medium-low heat. Add onion and cook until lightly browned. Add garlic and ginger and cook for a further 2 mins.
Add diced capsicums, korma paste and cook for another 2-3mins.
Stir in coconut milk and chicken stock. Return the chicken to the pan. Bring to the boil. Reduce heat to low and cook covered for 20 mins or until chicken is cooked through.
Add diced mango and cook 3-4 mins.
At the end add sour cream to thicken the curry and cook 2-3 mins.
Serve curry with steamed basmati rice, green beans, lime wedges and topped with chopped spring onions.