Heat oil in a saucepan and add whole cumin. When it crackles add onion and green chillies. Fry onion till soft and light brown.
Add ginger & garlic paste and tomatoes. Fry till tomatoes melt and oil starts to separate.
Now add spices like turmeric, red chili , cumin powder and coriander powder along with vegetable stock cube.
Cook for a minute add potatoes. Stir fry well on high heat and add little water if needed.
Add salt, lemon juice and tomato puree along with some water, close the lid and cook for 5 minutes on low heat.
When potatoes are 80 % cooked add capsicum and garam masala powder. Stir well cook for 2 more minutes with the lid on.
Taste and check the seasoning. And finally add fresh coriander leaves stir and switch off the gas.
Serve hot with rotis, puri or phulkas.
Can also be served as a side dish with steamed rice.