Heat the
oil in a wok or frying pan, add the cumin seeds and
onion, and fry until the onion is lightly browned.
Stir in the tomatoes and fry for a few seconds, then add
the ground coriander, chili powder, sugar and salt and
stir well. Lower the heat and cook for about 5-7
minutes.
Add
the beans, stir carefully but thoroughly and cook for
10-15 minutes. Serve immediately.