Cut chicken thigh fillets into pieces. Combine flour and cumin in bag, shake well.
Add chicken to bag in batches, shake off excess flour.
Heat oil in large pan, add chicken to pan in single layer, stir over high heat until well browned all over, remove from pan.
Repeat process with remaining chicken thigh fillets.
Clean pan, add ghee, heat; add onions, cook, stirring until light golden brown.
Add garam masala, curry powder and extra cumin, cook 1 minute, stirring;
Add garlic, ginger and sugar, cook further 1 minute, stirring.
Return chicken to pan with chicken stock, bring to the boil, cover, reduce heat, simmer 1 hour, stirring occasionally. (If preferred, chicken can be cooked in an overproof dish in a moderate oven for 1 hour).
Stir combined yoghurt, coconut cream and lemon juice into chicken, reheat without boiling.
Curry can be made the day before required. Chicken mixture can be frozen for up to two months, add yoghurt mixture after thawing and reheating.
