Cut the chicken into small pieces. Heat the oil and fry the finely chopped onions, garlic and ginger. When they begin to turn color, add the spices and cook for a few minutes longer. Add the tomatoes and salt to taste and cook for a further 5 minutes. Put in the chicken pieces and stir so that they are thoroughly coated with the sauce. Cover and simmer for about 3 minutes.
At the end of this time the mixture should be almost dry, but you need to check from time to time and add a little water if necessary