Heat 1 tablespoon of oil in a large saucepan, add the onion, garlic and curry paste. Cook for 2-3 minutes. Add the coconut milk, stirring all the time, then the lemon grass, lime leaves, yogurt, cream and chutney. Bring to the boil and simmer for 30 minutes. Liquidise and sieve. Return the sauce to a clean pan. Thicken the sauce by mixing the flour with 3 tablespoons cold water. Add to the sauce whilst stirring, and return to the boil. Heat the remaining oil in a large frying pan and fry the chicken pieces for 2-3 minutes. Add the cooked chicken pieces to the sauce and heat gently. Serve with rice or noodles. NOTES : This delicious spicy Thai curry is ideal served with Thai fragrant rice.