Heat oil in a medium-size pan over medium-high heat.
Once the oil is hot, add cumin seeds and let them crackle for 3-4 seconds.
Add onions and ginger-garlic paste to the pan and fry for 2 minutes, stirring frequently.
Add potatoes and mix well. Reduce the heat to low.
Cover the pan with a tight-fitting lid and cook until the potatoes are tender (10-12 minutes). Stir a few times while cooking.
Splash a tablespoon of water if the potatoes are getting burned.
Remove the lid and add coriander powder, turmeric powder, Kashmiri red chili powder, and salt to the pan and mix well.
Add tomatoes and cook for 3-4 minutes until the tomatoes are mushy.
Add bell peppers and mix well.
Cover the pan again and cook on low heat for another 8-10 minutes.
Remove the lid. Add dry mango powder and mix well.
Check for salt and add more if needed. Garnish with fresh coriander (cilantro) and serve hot.