Heat oil in a saucepan and add cumin seeds. Fry until aromatic.
Add onions and sauté on medium heat for 5 to 7 minutes until soft and translucent.
Lower heat and add crushed ginger and garlic. Fry for 30 seconds or until fragrant.
Add diced tomatoes, salt and ground spices (turmeric and red chili powder). Increase heat to high and fry until the tomatoes soften, about 5-7 minutes.
Add chopped green beans and mix well.
Add the diced potatoes and continue to sauté on high heat for 5-7 minutes.
Lower heat to medium, cover the pan with a tight fitting lid and let the potatoes steam until ready.
Remove from heat. Serve with roti or daal chawal.