Heat some oil in a small pressure cooker (optionally, you can also use a pan with a lid if you are using boiled potatoes). Add mustard seeds (rai) to the cooker. When they start to crackle, add cumin seeds (jeera). Fry the cumin seeds for a few seconds till they start to splutter. Add a pinch of asafoetida (hing).
1/2 Teaspoon Rai (Black Mustard Seeds), 1/2 Teaspoon Cumin Seeds (Jeera), 1/4 Teaspoon Heeng (Asafoetida)
Turn the flame to low and add turmeric powder (haldi), red chilli Powder and coriander powder (dhania powder), garam masala and salt. Make sure that the flame is low as these spices will otherwise get burnt in hot oil.
1/2 Teaspoon Turmeric Powder (Haldi), 1/2 Teaspoon Red Chilli Powder, 1/2 Teaspoon Coriander Powder (Dhaniya Powder), 1/4 Teaspoon Garam Masala, 1 Teaspoon Salt
Also add a few curry leaves (curry patta) along with finely chopped pieces of ginger (adrak) and green chilies (hari mirch).
1 Inch Ginger (Adrak), 5-6 Curry Tree Leaves (Curry Patta leaves), 1-2 Green Chili cut into pieces (Hari Mirch)
Now add chopped pieces of Tomato or tomato puree.
3 Medium Sized Tomatoes
Sauté till the tomato pieces become soft and you can see oil leaving the sides.
Add chopped potatoes (about one inch size) followed by 1 1/2 cup or 1 glass of water. Mix well and cook till you get one whistle of pressure cooker. Allow some time to cool so that steam escapes from the pressure cooker and the lid can be safely opened.
3 Medium Sized Potatoes
Add dried fenugreek leaves (kasuri methi) and also garnish with fresh coriander leaves (hara dhaniya). Optionally a teaspoon of milk cream can be added to give a rich look to the curry. Aloo Tamatar Ki Sabzi is ready. Serve it hot with roti, paratha or pooris.
1/4 Teaspoon Kasoori Methi (Dried Fenugreek Leaves), 8-10 Coriander Leaves (Cilantro or Dhaniya)