Heat oil in pan, add onions, ginger, garlic, salt, turmeric, cardamom, bay leaf, chili, cinnamon and cumin. Fry for 2 minutes. Cover pan, reduce to low and simmer for 10 minutes. Uncover and fry for 1 minute. Add chicken and stir well for 2 minutes. Add water and cook for 30 minutes. Add tamarind liquid and sugar and stir well. Cover and cook over low heat to create a thick onion sauce. Stir occasionally and serve with pilau or just plain rice.