Heat Oil in the pan and add cumin seeds.
Allow the cumin seed to crackle and add grated ginger.
Add whole red chili and green chili and stir.
Add sliced onion and saute them for few minutes and add cut pieces of potatoes in the pan.
Cover the pan and cook potatoes for 5-6 minutes before adding capsicum / Shimla mirch as the potatoes take little longer to cook.
Add Shimla mirch or capsicum and cook for 2-3 minutes more.
Now after 5 minutes add salt, red chili powder, turmeric powder, coriander powder, cumin powder and chaat masala powder.
Add chopped tomatoes and mix everything well.
Cover and cook for 5-6 minutes more on medium heat and stir it once or twice in between.
Aloo Shimla mirch is ready to serve with Hot phulka or paratha.