put oil in wide pan and set over medium high heat. when oil is hot, add cumin seeds. as soon as seeds begin to sizzle, add onion. stir and fry till onion browns. add ginger and garlic. stir until garlic starts to brown.
add mushrooms. stir and fry for 2 minutes. add beans, ground coriander, ground cumin, turmeric, garam masala, cayenne, salt, tomato, and 1/2 c water.
bring to boil; cover, lower heat and simmer for 15 minutes.
remove cover, raise heat, and boil most of liquid away, stirring gently as you do.